The home page pa11y.org has some errors.
After H1 the next header element is H3 This is wrong.
WCAG tell that links shall been underlined.
<main role="main"> is strange the explicit role of <main> is always main! The role declaration is, for this case, not needed. Aria is only to be used if neccessary.
The same apply to <nav class="site-nav" role="navigation" aria-label="Main Navigation">