You can set your spawn point inside an end portal, causing the player to become stuck in the End

The Bug

Players who place a bed on an active portal's frame OR sleep or set their spawn point and jump into the portal can become permanently stuck within the end.

How To Reproduce

By [Helper] pine1needle in this comment

1. Place a bed next to an end portal in a stronghold. Right click the bed to set your spawn point. Here's a fast way to arrive at an end portal in a stronghold.

   Seed: 4
   /execute in minecraft:overworld run tp @s -1000.75 39.00 800.18 179.40 27.90
   

2. Place any valid spawnable block beneath the portal.
3. Eliminate any alternative spawnable blocks that the bed could place you on when you respawn.
4. Complete the portal using eyes of ender. Enter the end portal.

5. /kill @e[type=ender_dragon]

6. Enter the return portal. Skip the credits by pressing "escape" on your keyboard.
   → You're instantly sent back to the end.
7. Jump into the void and then click "Respawn".
   → You're instantly sent back to the end.