Lava ignites surrounding blocks while being fully covered

[DaDokk66]

Description

when I was building my airship, the baloon ignited. I have a dripstone lava generator below the spot where it ignited. But the lava is fully covered with blocks.

Game Log

https://mclo.gs/Qo1MWtH

[copygirl]

Have you tried this in Vanilla / outside a contraption?
Lava doesn't care if it's covered or not. (source)