I swear, for the majority of the development time, I was using THIS to check for negative numbers:
str(move.y).begins_with("-")
What that means is I was converting the characters vertical velocity into a string and checking if the first character was a minus sign.
._. Don't laugh, I was in a hurry.
I eventually went on Reddit for help on an unrelated bug and got schooled on that and other crappy code lol. Thank you random Reddit user for making my game run better.