Not sure how this glitch really works, but the way it happened for me was basically i had a command block which gave you infinite regeneration and health boost (99999 seconds 255 amount) and standing on pressure plates gives you it. Then exiting the building will remove health boost and regen with more command blocks. But for some reason, removing the health boost kills you but you dont respawn in your spawnpoint, you respawn in the exact place where the pressure plate was and your character is stuck in it's lying down dead with the weird red filter and you can still walk but it is very weird. You have to actually die in order for it to stop. I think something similar to this might've been reported before but I couldn't see it anywhere so very sorry if there has been.