Legal Question in Business Law in Michigan

I find it funny how none of the options you allude to includes just letting them know they overpaid and giving them their money back. If you keep it and they discover that later they can sue you back for it. They can also report it as a crime although it would be very hard to prove you intended anything... of course you do admit to that here, however. If it was the platform that overpaid and not the customer they may also close your account with them, if that matters to you.

And if it was the customer that overpaid, why would you want to take advantage of someone who actually honestly transacting with you? It's akin to stealing from your mom. Even if it was the platform, you should not keep what is not yours to keep as a general rule.