I carry mine in my wallet and hope the adjoining moth eaten $1.00 bills will protect it. My best guess is apps/passports will draw from the state vaccination databases because cards are so easy to fake. Check with your state health department vaccination records and make sure they updated your records.
I went to Kauai in March with their island-specific “resort bubble” testing and quarantine rules and none of the authorities ever asked for my vaccination records. The testing results were uploaded into govt. specified apps which had to be shown to check into a hotel, rent a car, etc… I am guessing vaccination records will be handled in similar fashion.