1.16.3, 21w03a, 1.16.5, 21w05b, 21w07a
If a skeleton shoots an arrow through some lava/fire or uses a flame bow, the flaming arrow can explode TNT even if /gamerule mobgreifing is set to false.
How to reproduce:
- Spawn in a skeleton and trap it.
- Place a block of TNT nearby
- Place some lava in between the skeleton and the TNT
- Switch to survival and stand near the TNT until the skeleton hits it.