Google Pixel 7a Fingerprint Unlock POOR - Possible Fix!
A possible thing to try to make your fingerprint unlock more reliable on the Google Pixel 7a.
Delete all saved fingerprints and save the same finger or thumb twice.
This might allow better accuracy by saving two profiles per digit.
Save the second fingerprint profile in the dark as well to allow better results.
This does mean you can only have two digits saved of course since the phone only allows up to 4 profiles to be saved.
Perhaps there will be a fix for this in a future update.