See if you can piece together what happened from paystubs.  It could be as simple as an erroneous W-2.  Ooh, that reminds me, I haven't found a W-2 error yet this year.  Usually there's at least one every year...

I don't know that I've ever had a client who spent the exact amount on daycare as they contributed to an FSA.  Usually daycare expenses are much higher.  I did have some weird carryover issues with a few 2020 returns.