When a card is entered into Apple Wallet these are usually the basics that are done to make sure the card is valid.
- Basic checks — card number, card is on Payment Network, card is active,
- CVC verification — issuer validates security code
- AVS Check — Address Verification Service determines validity and matches address provided and known addresses
- Velocity check - (optionally) tried to enter card too many times
The bank and Payment Network Operator (Mastercard , Visa etc.) perform those checks. If they fail, the card is <Invalid>.
Did you remember to activate the new card? Have you recently moved and an address is incorrect? Have you recently travelled and your iPhone is set to the wrong region/country? Are you using a VPN or have antivirus or security software installed?