A chargeback is the card network's dispute mechanism: a cardholder contests a charge with their bank, and the bank claws the money back from the merchant while the dispute is decided. The merchant — in rent terms, the landlord or the platform collecting on their behalf — can contest it with evidence, but the funds are gone in the meantime, and losing the dispute makes the reversal permanent, usually with a dispute fee on top. Chargebacks exist to protect consumers from fraud and billing errors, and they apply to card payments; the ACH world has its own separate return and dispute process.
For rent collection, chargebacks are one reason card payments behave differently from bank transfers: a card payment that cleared weeks ago can still be disputed, and "rent paid by card, then charged back" leaves the landlord holding both a housing obligation and a payment reversal. The defenses are ordinary hygiene — a clear lease, a rent ledger that documents what each charge was for, and receipts — plus treating any chargeback as both a bookkeeping event to reverse cleanly and a tenant conversation to have promptly.