About 18 months in to a very gently used doorbell. Microcracks started forming only a few months in, but it was along the edges and barely noticable. Now, the enture surface is covered, obscuring the cameral. It appears that the top layer of the “glass” is flaking off.
I had to remove the doorbell for fear that someone would actually injur themselves on the cracked glass when attempting to hit the button.