Time warp ending:
Defeat jevil/??? (doesn't matter how you do it) then go to the bazaar and go to the the stand covered in carpets.
The person selling the overpriced items is replaced with a shadowy figure. Open the bunker, and the shadowy figure will sell an item called the reality warper band.
Buy the band, go to any level in the backrooms, and use it.
You'll then find yourself in a giant void with multiple floating balls of light. Go into one of the balls and you'll get your ending.
Time warp ending/Press start?