As stated, this is a scam.
Turn off automatic acceptance of Apple Cash deposits, as it cuts down on the unexpected-cash scams.
Only accept money you are expecting and only from those you know.
One fairly common payment scam pattern is a (fraudulent) payment from a stolen card, followed by a request for a partial refund by the scammers, and the payment provider then eventually claws back the original (fraudulent) payment, leaving you without the original (fraudulent) transfer and without whatever cash you “refunded” to the scammers.
As for the money, leave it where it is, don’t transfer it and don’t spend it, pending confirmation through other and identifiable and verifiable means of payment notifications, or its eventual disappearance through clawback, or whatever else happens.
Assume the “bank error” is never in your favor, as the old joke goes. If it’s still there after say three months with no other activity, then you have money. Probably.
How to turn off Apple Cash automatic payment acceptance on iPhone:
Settings > Apps > Wallet > (Payment Cards) Apple Cash > Info (not Transactions) > (Accepting Payments) Manually Accept Payments