Entities interacted despawn after crashing

I crashed in a singleplayer survival world
1. while fighting the wither
2. after trading with villager

When I rejoin the world,
Expected result: the wither that I interacted with before crashing would still remain in its position; the villager stays there
Actual result: the wither despawns; the villager despawns (villager had nametag)

Please fix the above bug. It is very obnoxious especially when you spent 10 h in the nether for skulls but your effort is wasted later.

Device: iPad 6th Generation (not iPad Pro, please add an option to that)