Even after beating I'm not entirely sure what happened, maybe it's supposed to be in some sort of paradox room like Recursed has?
It's a real room next to the first one, just like the earlier levels.
Explanation of the solution below:
Player moves into the right room, resetting the left.
Player attempts to reset itself because it's not immune [green], but its position is blocked.
Now 'dead', the player respawns, on the spawn point that's still in the un-reset right room.