What is this under the glass and in front of the camera and sensor?

I think this is UbreakIfix's fault as it appeared after they repaired cracked glass on the phone.

It originally appeared within the first month after they repaired it, but when I brought it back they refused to do the glass over again. Instead they put it in a desiccator? Which seemed to resolve the camera issue bit now a couple of months later I started having issues that I believe are related to the proximity sensor.

I sent to Google and they denied to fix saying water damage?

I never dropped the phone in water and the most water it's ever seen is from a little rain while I held it when it started raining.

Is this water damage? Is there any “trick” I can do to fix this without totally disassembling the phone myself, or am I screwed?

Thanks everyone

-Dave