Weird animated floor transition loading screen/cutscene I've never seen before

[chemicalchords]

Sorry, but I searched a ton for this and I couldn't find anything on it, but I'm very curious about it. I was just screwing around in Greedier mode and I got a Blank Card/Jera break. After a while I got bored so I went to the next floor and the loading screen was this weird animation of 3 characters (Isaac or somebody in a superhero mask and two other characters) merge together or something.

It's 5:30AM so I kind of missed what happened, but at first the screen was yellow or gold and I thought the game bugged out, but it turned into that animation. Has anybody else seen this before? I swear I'm not crazy!

[Nazemec]

I assume you just got all three bum items (coin, heart, and key bums), so they merged into the Super Bum. Getting this at a floor transition is odd though, maybe you picked up MissingNo and it (surprisingly) rerolled three of your item into that trio?

Wiki page: https://bindingofisaacrebirth.gamepedia.com/Super_Bum_(Transformation)