As I mentioned, inside the end in my case, I invoked a wither to get the star item, all good until there until I defeated it and I left the end (I had already defeated the dragon before), but I came back moments later back to the end portal and resulting in that the wither had regenerated again and I defeated it again but within the same cycle the wither does not stop appearing with half life inside the end even when defeating it it does not stop appearing leaving and entering the end, not even with peaceful difficulty it disappears (if all the mobs disappear but removing the option again, return together with the wither) not even with commands it stops appearing

I hope I have explained comprehensively and can fix this bug, thank you.