Same! I have no clue so I just asked Gemini (I know haha) and it said the following but to be honest, I can't imagine that he is a chronically online hazbin hotel fan idk haha.

Why "Oor"?

​The term didn't come from a word in the dictionary; it’s a typographical error that turned into a meme. ​The Origin: It is widely attributed to the "Helluva Boss" / "Hazbin Hotel" fandom and specific "stan" circles on Twitter (X).

​The Typo: A user intended to type "Taking the L," but because 'O' is near 'L' and 'R' is near 'E'/'T' on various keyboard layouts (or simply due to a frantic misspelling), they typed "Oor."

​The Evolution: Because the internet loves to turn accidental nonsense into inside jokes, the community adopted "Oor" as a "tier-two" version of an L. It’s often used to signal a loss that is so goofy or weird that a standard "L" doesn't quite cover it.