
Most Xiaomi phones now have a fingerprint reader, a way of gaining access to the phone. Hence, it is something everyone uses on a daily basis, meaning fingerprints unlock issue will affect their experience with the phone. Unfortunately, a recent update has broken this functionality for many people, and it does not seem a fix is on the way.
According to the latest HyperOS weekly bug report, many users cannot unlock their devices using the biometric authentication method. It is a bug that currently affects three phones in multiple regions, meaning that many are affected. You would expect a fix to be on the way, but Xiaomi is taking time to investigate before releasing a bug fix.
Xiaomi phones are affected by the fingerprints unlock issues

Xiaomi 14, Xiaomi 14T Pro, and POCO X6 Pro all have the fingerprint unlock issue. It seems to be affecting users in multiple regions. To know the countries experiencing this problem, we recommend the source link. You will also find out the build version that is affected and perhaps why your fingerprint has been messing up.
While we expect a fix, Xiaomi does not seem to be working on that presently. The company is still investigating the bug, and after the cause is confirmed, only then can they start working on a fix. However, it is something that can happen very fast, and hence, we believe a fix can begin rolling out very soon. Perhaps you can check the updater app to see if an update has already been released, as sometimes, Xiaomi can be swift.
source: Xiaomi Community