After entering the room, turn to face the from the entrance. You’ll see a wall that looks slightly different from the rest—it has visible cracks and a lighter stone texture.
The 4-2 secret is classic Ultrakill design: punishing, clever, and completely missable if you play “normally.” Now that you know where it is, you can grab it in under 10 seconds on your next run. ultrakill 4-2 secret