Steps to reproduce:
- Place a TNT on the ground.
- Place a second TNT on top of it or beside it.
- Using flint and steel, ignite the first TNT.
The second TNT ignited but is not launched away by the explosion. However, if the block supporting it is destroyed, it will fall as usual.
The second TNT is ignited and launched away from the explosion. It explodes after flying some distance away.