I had two Samsung flagship phones, one (S20FE) had an optical fingerprint reader and the other (S22) had an ultrasonic one. Both of them somewhat regularly failed to read my finger, were slower than a fingerprint reader on the power button and are more expensive/complex to build. They won’t work with cheap 3rd party screen replacements and some screen protectors as well.
Meanwhile my $90 Android phone has a fingerprint reader on the power button. It never fails and I never have to perfectly place my finger on the sensor area to get it to work. It just seems like the perfect place to put a fingerprint sensor, so why do phone manufacturers keep using in-display fingerprint readers over the cheaper alternative?
I will admit when I went to the Dark Side I was shocked by how much I like Face ID. I do miss having the in-screen fingerprint reader when I’m wearing a mask, SOMETIMES, but even that has improved in the time I’ve owned an iPhone.
But yeah, on my OnePlus 6T McLaren Edition and OnePlus 7T Pro 5G McLaren Edition (damn I loved those phones so much) the in-screen reader was excellent.
I use my phone on 10% brightness, in a completely dark room often (every day, every morning, every night). Not sure about you, but I guess face-ID doesn’t work then.
In my experience iPhone FaceID works fine at night, with brightness all the way down. It shines infrared at you (you can vaguely see some light red emitting from next to the camera, some bleed from the infrared) and then captures that with the camera. It might also use LiDAR, I’m not totally sure. It even unlocks while I’m wearing my CPAP, believe it or not, because since the updates to make it work with masks it pays more attention to the area around the eyes.
11 pro and never had this problem. Screen dimmed to minimum and Night Shift turned on, it still unlocks just fine.