Only in the case of a mistake or fraud. So if the recipient got the right amount in their account: it’s a done deal, same day.

As opposed to ACH which could bounce or you could issue a stop payment.

The definition of mistake is quite broad. Not all parties may agree to what is and isn’t, requiring litigation, but the transfer itself isn’t a done deal until a very lengthy process has been exhausted.

Zelle can't be undone if it's done from your account. They just take the money.

Of course it can. Zelle and your bank may not be keen on doing it, but it’s no less reversible than any other transfer.

And for fraudulent transfers, Zelle’s trying to pin them on the customer is them hoping you’d give up rather than remind them that regulation E governs it as well, and they used to acknowledge that on their web site.