The Android 10 rollout for the Mi A3 has been catastrophic, with Xiaomi pulling the initial build just a few days after unexpectedly releasing it over the weekend. If you are one of the unlucky few to have upgraded your Mi A3 to Android 10, then you are probably encountering plenty of bugs. There is a workaround for getting a functional fingerprint scanner back though, if that is any help.
https://www.notebookcheck.net/Fingerprint-scanner-not-working-on-your-Xiaomi-Mi-A3-after-upgrading-to-Android-10-There-is-a-workaround.455227.0.html