The Bug:
Sculk sensors are not activated upon fire or lava burning items.
Steps to Reproduce:
Throw an item into fire or lava.
→ ❌ Notice how when the item burns, the sculk sensor does not activate.
Additional Information:
Please note that the item must not hit the ground in order to reproduce this issue. Quote from the 20w49a Changelog, "A vibration is anything that causes physical motion". I would definitely consider this as physical motion, as an item is physically burning.
Can confirm