Do banks buy back gold coins?

Excuse me, I've been hearing some rumors about banks purchasing back gold coins. Could you please clarify if this is indeed the case? Are there any specific banks or institutions that engage in this practice? If so, what are the conditions or requirements for them to buy back the gold coins? Additionally, are there any advantages or disadvantages for individuals who choose to sell their gold coins back to banks? I'd appreciate any insights you could provide on this matter.