Quark wood variant chests adjacent to flammable material (either as flooring or as a wall) are destroyed when said wall or floor is on fire, and the fire "spreads" to where the chest is.

I have not exhaustively tested all chests in quark, but it appears to only affect wooden ones from quark. Vanilla chests, the nether brick and purpur ones appear unaffected after multiple tests.

Log file: https://pastebin.com/h2Ewhp4r

Versions:

Minecraft: 1.18.2
Forge versions: 40.1.68 (original version in pack) / 40.1.80 (latest available for 1.18.2 at time of report) / 40.1.0 (Latest recommended version at time of report)
quark: 3.2-358
AutoRegLib: 1.7-53

Also confirmed on 1.19.2
Minecraft: 1.19.2
Forge: 43.1.1 (recommended version at time of report) and 43.1.33 (Latest version at time of report)
Quark: 3.3-371
AutoRegLib: 1.8-54

Attached is a video of the test case I used to replicate the issue across all 3 Forge versions.