diff --git a/src/wp-admin/includes/class-wp-site-health.php b/src/wp-admin/includes/class-wp-site-health.php
index dd537296a8655..57fb92a67a5a5 100644
--- a/src/wp-admin/includes/class-wp-site-health.php
+++ b/src/wp-admin/includes/class-wp-site-health.php
@@ -3378,22 +3378,20 @@ public function is_development_environment() {
 	}
 
 	/**
-	 * Returns a list of headers and its verification callback to verify if page cache is enabled or not.
-	 *
-	 * Note: key is header name and value could be callable function to verify header value.
-	 * Empty value mean existence of header detect page cache is enabled.
+	 * Returns a mapping to response headers to an optional callback to verify if page cache is enabled or not.
 	 *
 	 * @since 6.1.0
 	 *
-	 * @return array List of client caching headers and their (optional) verification callbacks.
+	 * @return array<string, ?callable> Mapping of page caching headers and their (optional) verification callbacks.
 	 */
-	public function get_page_cache_headers() {
+	public function get_page_cache_headers(): array {
 
 		$cache_hit_callback = static function ( $header_value ) {
-			return str_contains( strtolower( $header_value ), 'hit' );
+			return (bool) preg_match( '/\bhit\b/i', $header_value );
 		};
 
 		$cache_headers = array(
+			// Standard HTTP caching headers.
 			'cache-control'          => static function ( $header_value ) {
 				return (bool) preg_match( '/max-age=[1-9]/', $header_value );
 			},
@@ -3403,26 +3401,54 @@ public function get_page_cache_headers() {
 			'age'                    => static function ( $header_value ) {
 				return is_numeric( $header_value ) && $header_value > 0;
 			},
-			'last-modified'          => '',
-			'etag'                   => '',
+			'last-modified'          => null,
+			'etag'                   => null,
+
+			// Custom caching headers.
 			'x-cache-enabled'        => static function ( $header_value ) {
 				return 'true' === strtolower( $header_value );
 			},
 			'x-cache-disabled'       => static function ( $header_value ) {
 				return ( 'on' !== strtolower( $header_value ) );
 			},
-			'x-srcache-store-status' => $cache_hit_callback,
+
+			/**
+			 * OpenResty srcache-nginx-module.
+			 *
+			 * The `x-srcache-store-status` header indicates if the response was stored in the cache.
+			 * Valid values include `STORE` and `BYPASS`.
+			 *
+			 * The `x-srcache-fetch-status` header indicates if the response was fetched from the cache.
+			 * Valid values include `HIT`, `MISS`, and `BYPASS`.
+			 *
+			 * @link https://github.com/openresty/srcache-nginx-module
+			 */
+			'x-srcache-store-status' => static function ( $header_value ) {
+				return 'store' === strtolower( $header_value );
+			},
 			'x-srcache-fetch-status' => $cache_hit_callback,
 
-			// Generic caching proxies (Nginx, Varnish, etc.)
-			'x-cache'           => $cache_hit_callback,
-			'x-cache-status'    => $cache_hit_callback,
-			'x-litespeed-cache' => $cache_hit_callback,
-			'x-proxy-cache'     => $cache_hit_callback,
-			'via'               => '',
+			// Generic caching proxies (Nginx, Varnish, Squid, Go, Fastly, LiteSpeed, etc.).
+			'x-cache'                => $cache_hit_callback,
+			'x-cache-status'         => $cache_hit_callback,
+			'x-litespeed-cache'      => $cache_hit_callback,
+			'x-proxy-cache'          => $cache_hit_callback,
+
+			/**
+			 * Varnish Cache.
+			 *
+			 * For a cache hit, it includes both the ID of the current request and the ID of the request
+			 * that populated the cache. For a miss, it only includes the current request ID.
+			 *
+			 * @link https://vinyl-cache.org/docs/2.1/faq/http.html
+			 */
+			'x-varnish'              => static function ( $header_value ) {
+				return (bool) preg_match( '/\d+ \d+/', $header_value );
+			},
+			'via'                    => null,
 
-			// Cloudflare
-			'cf-cache-status' => $cache_hit_callback,
+			// Cloudflare.
+			'cf-cache-status'        => $cache_hit_callback,
 		);
 
 		/**
@@ -3430,9 +3456,9 @@ public function get_page_cache_headers() {
 		 *
 		 * @since 6.1.0
 		 *
-		 * @param array $cache_headers Array of supported cache headers.
+		 * @param array<string, ?callable> $cache_headers Mapping of page caching headers and their (optional) verification callbacks.
 		 */
-		return apply_filters( 'site_status_page_cache_supported_cache_headers', $cache_headers );
+		return (array) apply_filters( 'site_status_page_cache_supported_cache_headers', $cache_headers );
 	}
 
 	/**
diff --git a/tests/phpunit/tests/admin/wpSiteHealth.php b/tests/phpunit/tests/admin/wpSiteHealth.php
index 2d32bbb14ec4d..05761765b327c 100644
--- a/tests/phpunit/tests/admin/wpSiteHealth.php
+++ b/tests/phpunit/tests/admin/wpSiteHealth.php
@@ -12,10 +12,8 @@ class Tests_Admin_wpSiteHealth extends WP_UnitTestCase {
 	 * An instance of the class to test.
 	 *
 	 * @since 6.1.0
-	 *
-	 * @var WP_Site_Health
 	 */
-	private $instance;
+	private WP_Site_Health $instance;
 
 	public static function wpSetUpBeforeClass( WP_UnitTest_Factory $factory ) {
 		// Include the `WP_Site_Health` file.
@@ -172,7 +170,7 @@ public function data_cron_health_checks() {
 	 * @covers ::get_page_cache_headers()
 	 * @covers ::check_for_page_caching()
 	 */
-	public function test_get_page_cache( $responses, $expected_status, $expected_label, $good_basic_auth = null, $delay_the_response = false ) {
+	public function test_get_page_cache( array $responses, string $expected_status, string $expected_label, bool $good_basic_auth = false, bool $delay_the_response = false ) {
 		$expected_props = array(
 			'badge'  => array(
 				'label' => __( 'Performance' ),
@@ -183,7 +181,7 @@ public function test_get_page_cache( $responses, $expected_status, $expected_lab
 			'label'  => $expected_label,
 		);
 
-		if ( null !== $good_basic_auth ) {
+		if ( $good_basic_auth ) {
 			$_SERVER['PHP_AUTH_USER'] = 'admin';
 			$_SERVER['PHP_AUTH_PW']   = 'password';
 		}
@@ -219,7 +217,7 @@ function ( $response, $parsed_args ) use ( &$responses, &$is_unauthorized, $good
 					);
 				}
 
-				if ( null !== $good_basic_auth ) {
+				if ( $good_basic_auth ) {
 					$this->assertArrayHasKey(
 						'Authorization',
 						$parsed_args['headers']
@@ -263,9 +261,15 @@ function ( $response, $parsed_args ) use ( &$responses, &$is_unauthorized, $good
 	 *
 	 * @ticket 56041
 	 *
-	 * @return array[]
+	 * @return array<string, array{
+	 *     responses: array<int, string|array<string, string|string[]>>,
+	 *     expected_status: 'recommended'|'critical'|'good',
+	 *     expected_label: string,
+	 *     good_basic_auth?: bool,
+	 *     delay_the_response?: bool,
+	 * }>
 	 */
-	public function data_get_page_cache() {
+	public function data_get_page_cache(): array {
 		$recommended_label = 'Page cache is not detected but the server response time is OK';
 		$good_label        = 'Page cache is detected and the server response time is good';
 		$critical_label    = 'Page cache is not detected and the server response time is slow';
@@ -278,13 +282,13 @@ public function data_get_page_cache() {
 				),
 				'expected_status' => 'recommended',
 				'expected_label'  => $error_label,
-				'good_basic_auth' => false,
+				'good_basic_auth' => true,
 			),
 			'no-cache-control'                       => array(
 				'responses'          => array_fill( 0, 3, array() ),
 				'expected_status'    => 'critical',
 				'expected_label'     => $critical_label,
-				'good_basic_auth'    => null,
+				'good_basic_auth'    => false,
 				'delay_the_response' => true,
 			),
 			'no-cache'                               => array(
@@ -310,7 +314,7 @@ public function data_get_page_cache() {
 				'responses'          => array_fill( 0, 3, array( 'cache-control' => 'no-cache' ) ),
 				'expected_status'    => 'critical',
 				'expected_label'     => $critical_label,
-				'good_basic_auth'    => null,
+				'good_basic_auth'    => false,
 				'delay_the_response' => true,
 			),
 			'age'                                    => array(
@@ -366,7 +370,7 @@ public function data_get_page_cache() {
 				),
 				'expected_status'    => 'critical',
 				'expected_label'     => $critical_label,
-				'good_basic_auth'    => null,
+				'good_basic_auth'    => false,
 				'delay_the_response' => true,
 			),
 			'cache-control-with-basic-auth'          => array(
@@ -396,7 +400,7 @@ public function data_get_page_cache() {
 				),
 				'expected_status'    => 'critical',
 				'expected_label'     => $critical_label,
-				'good_basic_auth'    => null,
+				'good_basic_auth'    => false,
 				'delay_the_response' => true,
 			),
 			'x-cache-disabled'                       => array(
@@ -408,6 +412,78 @@ public function data_get_page_cache() {
 				'expected_status' => 'good',
 				'expected_label'  => $good_label,
 			),
+			'false-positive-hit-in-word'             => array(
+				'responses'       => array_fill(
+					0,
+					3,
+					array( 'x-cache' => 'shit' )
+				),
+				'expected_status' => 'recommended',
+				'expected_label'  => $recommended_label,
+			),
+			'varnish-header'                         => array(
+				'responses'       => array_fill(
+					0,
+					3,
+					array( 'x-varnish' => '123 456' )
+				),
+				'expected_status' => 'good',
+				'expected_label'  => $good_label,
+			),
+			'varnish-header-miss'                    => array(
+				'responses'       => array_fill(
+					0,
+					3,
+					array( 'x-varnish' => '123' )
+				),
+				'expected_status' => 'recommended',
+				'expected_label'  => $recommended_label,
+			),
+			'srcache-store-status'                   => array(
+				'responses'       => array_fill(
+					0,
+					3,
+					array( 'x-srcache-store-status' => 'STORE' )
+				),
+				'expected_status' => 'good',
+				'expected_label'  => $good_label,
+			),
+			'srcache-store-status-bypass'            => array(
+				'responses'       => array_fill(
+					0,
+					3,
+					array( 'x-srcache-store-status' => 'BYPASS' )
+				),
+				'expected_status' => 'recommended',
+				'expected_label'  => $recommended_label,
+			),
+			'srcache-fetch-status'                   => array(
+				'responses'       => array_fill(
+					0,
+					3,
+					array( 'x-srcache-fetch-status' => 'HIT' )
+				),
+				'expected_status' => 'good',
+				'expected_label'  => $good_label,
+			),
+			'last-modified'                          => array(
+				'responses'       => array_fill(
+					0,
+					3,
+					array( 'last-modified' => 'Wed, 21 Oct 2015 07:28:00 GMT' )
+				),
+				'expected_status' => 'good',
+				'expected_label'  => $good_label,
+			),
+			'via'                                    => array(
+				'responses'       => array_fill(
+					0,
+					3,
+					array( 'via' => '1.1 varnish' )
+				),
+				'expected_status' => 'good',
+				'expected_label'  => $good_label,
+			),
 		);
 	}