i remember having read one of those handouts from shul with a halachik discussion about receiving a forged bill, and if you could demand to be repaid…but not the conclusion.
The storekeeper actually is legally supposed to take the bill away from you if it’s forged, i think. Someone i know once took it back though and brought it to a bank where they told him it WAS real but looked like it had gone through a washer n dryer, so had shrunk a bit and looked off. He exchanged it for a fresh bill.