When a wither kills a mob, it creates a wither rose on the place where it died.
It shouldn't do that when mobGriefing is set to false, but it still does.
How to reproduce
- Set mobGriefing to false
/gamerule mobGriefing false
- Spawn a wither and a pig
→ The wither will kill the pig, and place a wither rose where it died.