I found this glitch recently while playing on my single player world.

How to replicate:

1. Place a bed in the Overworld and set your respawn point.
2. Go to the Nether, place a Respawn Anchor, and charge it up fully with 4 glowstone.
3. Do /kill 4 times until the Respawn Anchor is out of charge.
   • You will continuously respawn at the anchor as expected.
4. Do /kill one last time
5. You will now respawn in the Overworld at the original world spawn point as opposed to spawning by your bed.

I believe that as soon as a Respawn Anchor is used, it cancels out any other spawn points which makes sense. However, once there is no charge and the player dies one more time, the game no longer recognizes the players bed as the intended spawn point. This makes gameplay after dying in the Nether repeatedly a hassle if your base isn't close to the original world spawn.