When changing HUD settings on one world, any changes you make will persist between all worlds, realms, or servers you join afterwards, even ones where you do not have permissions.

How to reproduce:

On a world with moLang experiments and cheats enabled, type /hud @s hide all

Leave the world, and join any other world/realm/server.

All HUD (except hotbar which is inconsistent) will not appear.

This effect will continue until you relaunch minecraft, or go back into a world and re-enable hud manually.