For all those wondering:

“USC 333 - Paper Currency
This is the big one. It says anyone who “mutilates, cuts, defaces, disfigures, or perforates” a bank bill (that means your cash) with intent to render it unfit for reissue can be fined or jailed for up to six months.

The magic words? “With intent to render it unfit.” That’s what makes the difference.”

https://usfirstexchange.com/is-it-illegail-to-write-or-draw-money