"/attribute @s minecraft:generic.max_health base set 6" resets after leaving The End through portal.

I have set my health to 3 hearts in my hardcore world with the attributes command. Whenever I leave The End through the portal to The Overworld it resets and gives me 10 hearts which means I have to open LAN and enable cheats every time I leave The End. It seems to be a glitch, if intended, please change.