I mostly agree with IRMN (unless this is one of those posts where the facts keep changing when people don't like the answers they're given) but I am curious, what happened to the $7,000?  If the broker says they took it out of the account don't they either need to put it back when the check doesn't clear or reissue the uncashed check in some form?  How did the taxpayer know that the check was not cashed?

Some IRA accounts have a checkbook now so folks can write their own checks to charity.  These won't come out of the account until they clear the bank (because that's the only way the broker knows you wrote a check) so I strongly discourage clients from waiting until December to mail these things.

Starting in 2025 there's a new code "Y" for the 1099-R (see PDF page 9) for QCDs.  I haven't looked to see what the rules might be for how the broker knows which payments go to qualified charities and which don't.  But that's a next-year problem.  I'm guessing taxpayers will just "self-certify" (i.e. "check this box if you don't want the IRS to tax you on this distribution").

Rick