A Plaid balance check is NOT a guarantee that the ACH debit you're about to submit will go through.

I don't care if the balance is one million, before that ACH can process, every single dollar can be (a) wired out, (b) cleared out by yesterday's ACHs (bills, autopay, whatever) and checks, or (c) spent at debit/ATM.

I probably shouldn't tell you why I know that some fintechs don't address this.