After you file

@dmatth I know this is not a satisfactory answer but it is what the IRS says for why they are mailing you a check and not a direct deposit for the third stimulus.

 

IRS website for get my payment FAQ's - https://www.irs.gov/coronavirus/get-my-payment-frequently-asked-questions

 

Your payment may have been sent by mail because the bank rejected the deposit. This could happen because the bank information was invalid or the bank account has been closed.

Note: You can’t change your bank information already on file with the IRS for your first or second Economic Impact Payment. Don’t call the IRS, our phone assistors won’t be able to change your bank information, either.