Problem:

Both going into the End and exiting the End are bugged with some kind of damage/kill bug.

Entering the end has damaged me down to two hearts, only killing me if I was low HP before going in. Entering End damage was also inconsistent world to world, as some world's wouldn't damage and others would.

Exiting has a more drastic outcome, as you will die, no matter what HP, and lose everything you had in your inventory. Sometimes it can even soft lock the game by respawning you, yet keeping you in the death screen without any options to select. Ususlly having to force close the application. 

My tests:

Me and a friend had tried it in different worlds, and ended up with the same outcome. I even did it on MCPE on my phone and had the same outcome.

Final notes:

I'm surprised I couldn't find anouther ticket with the same issue, as this put a serious halt to me and my buddies realm. I can submit some videos if you would like to see this bug in action.