If you enter through a nether portal frame in the end, it summons your player at a y value of 32765, and into a "husk overworld".

Here are my findings:

• Teleporting to a set location (ex 0, 70, 0) using /tp will create a "husk" character of which entitys will try to attack. They can hit that ghost entity, but no damage is delt to the player.
• Using /summon or /fill will put the object or block you summoned in the position of your "husk".
• Trying to break blocks works, but nothing will drop and no breaking sound will play. The player can also place an infinite amount of blocks, even if they only have 1 in their hot-bar.
• It is impossible for the player to die, using fall damage, entity damage or even /kill does not work. (Edit note: Explosions do kill the player, and returns them back to the regular overworld.)
• Entering a portal does not work.
• You cannot damage entities.
• Bug fixes when reloading world, blocks you broke were never actually broken, and mobs will immediately start attacking you. You will spawn where your "husk" character last was.
• Entering the End through the Nether works as intended. The player will go to the end and can go back to the overworld once the dragon dies.
• Even though my video was recorded in 1.16.0.63, this bug is still active in 1.16.0.64