The Bug
I noticed this very odd behavior. You are able to get killed by mobs in creative as seen in the attachments below. It happens vice versa for survival: You do not get killed by mobs. Possibly relates to the player after death bug?
Steps to reproduce
Die in the Nether
Wait for mobs to come
Eventually you will be killed by one, it is usually invisible and/or has very peculiar behavior
Linked issues
duplicates 1
Attachments
Comments 3
Resolved as a duplicate of MC-176004
Could not reproduce in 20w13b? I think the issue got fixed?