iOS 14.7.1

Make sure that you have the latest version of iOS or iPadOS. Make sure that your fingers and the Touch ID sensor are clean and dry. ... Go to Settings > Touch ID & Passcode and make sure that iPhone Unlock or iTunes & App Store is on, and that you've enrolled one or more fingerprints. Try enrolling a different finger.

If Touch ID isn't working on your iPhone or iPad - Apple Support

I did have issues with TouchID with the App Store. Turns out when I updated to 14.7.1, it reset some settings on my iPad Pro. Including TouchID use for iTunes and App Store. It was confusing me for a couple of days. You don’t tend think to about something that you know has been working/on forever. Wish Apple made that bit of disclaimer.