https://wccftech.com/magic-keyboard-touch-id-wont-work-m1-ipad-pro/

In addition to being incompatible with Intel-based iMacs, the new Magic Keyboard’s Touch ID feature will not work on any M1 iPad Pro model that Apple announced yesterday. This is a strange revelation because Touch ID is designed to work with the new M1 iMac, but it does not work with a tablet that features the same chipset as Apple’s latest ‘All in One’.

Apple confirmed with MacRumors that the Touch ID chip would not function with the M1 iPad Pro. While many users will not require identification of their fingerprint when unlocking the iPad Pro, thanks to the addition of Face ID, customers will prefer being given a choice on how to access the tablet. Perhaps Apple would have thought that the inclusion of Face ID would make the Touch ID feature on the Magic Keyboard unnecessary when unlocking the iPad Pro.