Scammers are getting cleverer. My spouse was just nearly phished as they caught her by phone just out of the shower with a "fraud alert," and gave her enough information she gave them a little—before realizing they weren't legit. They offered her the first six digits of her card, which means they probably knew the card issuer but not the full number. They wanted her to read the full card and she called foul and then called the issuer, who confirmed nobody had called, and hard card replaced.
@glennf 6 digits will only identify the payment network (Visa, etc) and card issuer. If the card was from a major bank, they probably simply guessed it and got lucky.
@mansr Oh, I thought first four were network, not first six.
@glennf The first six digits are the Issuer Identifier Number. This identifies the payment network, card issuer, country, currency, type of card (debit/credit), etc. There's more info and a decoder at https://www.bincodes.com/.
BIN - Validate, Verify, Check, Calculate & Generate

Free online tools to check, validate, calculate & generate BIN - Bank Identification Number