So I’ve been messing around with a few phones lately, a nexus 6p, a pixel 3a xl, and a s21 ultra, and I’ve noticed that on the 6p and 3a xl both sound louder, punchier, and clearer when compared to the s21 ultra. They also both have that thicc notch design with a massive speakerphone which might add to the high volume levels.
Just out of curiosity, have you tried registering your prints in a darkened room?
I took your suggestion and went to a pitch black room and re-enrolled all fingerprints. No significant improvement.
Oh well, at least we tried!