The black eyed pet glitch

You might know the glitch where your animals eyes go dark, but this is about pets. Right now, the glitch is fixed (or is it? idk), but when you placed your pet in your den, its eyes would explode black. You might have experienced it yourself (and yes, it is real). In my experience I put a pet jerboa in my den, and gave it a sleeping area. I checked back later on my den, and the eyes of my pet were glowing black (but this does not only happen to jerboas. It would also happen to other pets too). When you would put the same pet that had its eyes black as a pet that would follow you, its eyes would turn back to normal. But since there's not a lot about it going around, I would just like to point it out here, in this wiki for now.