If you used the refund processing service and the check went to that bank (even though it was not supposed to ) and the processing bank tries to forward it to a closed account .... then the processing bank will either 1) return the money to the IRS and they will mail out a check OR 2) mail you a check to the address on your return. If you have also moved put in a forwarding with the post office asap.
Now the good news ... if the deposit is made to a dormant account and gets rejected then the money will be returned and be reissued as a check to the address on the last filed return. If you don't get the money by 1/20 then you will get it on the 2020 return you file next year.
Hot off the press ... straight from the horse's mouth ...
https://www.irs.gov/newsroom/treasury-and-irs-begin-delivering-second-round-of-economic-impact-payme...
