So I found one con to using UVC for N95 mask.

UVC will cause rapid deterioration of rubber.

So one of my N95 masks had it's rubber strap snap when putting it on. The rubber had visibly changed and become brittle.

My other mask from the same pack but also not subject to the UV were still pliable.

Of course, this was after about 10 times in the UV Microwave and a few of the times, I didn't have the vent fan running.

At first I thought it was generating ozone, but going back to the datasheet,  this tube is not supposed to create ozone. I did some research and UVC will cause photochemical change in plastics and rubber. (see FAQ at https://iuva.org/).