The fingerprint and facial recognition on the S21+ sucks. The phone rarely recognizes my finger or my face I usually have to go with the pattern. The iris scan on the Note 9 was better.
I have found that entering the same finger multiple times from different angles helps. Make sure screen sensitivity is off when you input your finger print and then turn it on when you are done.
I have a screen protector on my regular s21 and it works pretty much every time. The only time it doesn't is when my thumb has been exposed to moisture for a period of time. Usually takes about 3 tries to work.
I will give it a try againI did not know there was such a feature. I just turned mine on and while still not perfect it does seem to work a little better.
I will give it a try again