We received a letter from a bank where they are asking to return monies from a check that one of our customer's deposited in 2019 stating that it was "without entry-forged maker". Can anyone guide me to where I can find information on if we have to honor this request and time frames for returning? I am thinking we are not required to honor their request since it was back from 2019 but not sure on the rules.

If the other bank paid one of their on-us checks that involved a forged maker - then the loss falls on them. You would be under no obligation to do anything. Their claim (if any) would be directly with your customer that deposited it.

That's what I was thinking as well. Thanks!

Even in situations in which so-called "Rule 9" check fraud warranties are involved, it would be too late for the paying bank to press a breach of warranty claim under Rule 9.

The paying bank is either ignorant of the law/rules, or is hoping that your bank is ignorant so that it doesn't need to take a loss. In some states (Florida and Georgia, for instance), it might even be too late for THEIR depositor to press a claim that the check wasn't authorized.