(can’t even see what you said minutes ago)
Searching for touch ID glass gets lots of similar stories, some with self-destructive brittleness, but also your old posts where you relate Apple’s info that this surface is sapphire, the opposite of a glass.
About Touch ID advanced security technology - Apple Support
“The button is made from sapphire crystal—one of the clearest, hardest materials available. This protects the sensor and acts as a lens to precisely focus it on your finger. On iPhone and iPad, a steel ring surrounding the button detects your finger and tells Touch ID to start reading your fingerprint.
The sensor uses advanced capacitive touch to take a high-resolution image from small sections of your fingerprint from the subepidermal layers of your skin.”
But nothing protects the button. Nylon, which may be transparent, has thrise the Izod impact strength of alumina and deforms to transmit the impact into the frame. As the button is flat there is no “lens” or “focus” unless there’s a refractive index gradient which I doubt. It also seems the capacitive (C, V) touch and imaging (IR?) are conflated.
Apple’s replacement price is most of the tablet and Apple Care+, which is too late to get, is like insurance where others pay for one’s damages. I hav yet to see Best Buy’s repair quote but their flat fee is $85. Unlike most of the other reports my incident was a lucky split rather than dent on one end of the sensor where the finger doesn’t rest so the touch ID still works. I should save my money until I need touch during a failure.