u/WebSerious7105

For context, we replaced the ceiling fan in our living room about a year ago. The light fixture we replaced it with has a smaller "attachment" size so you can see the larger circle where the old fan's "attachment" was. Since the old fan was there for so long (10+ years), I figured the dark discoloration was just from time, dirt, etc. but I had an HVAC contractor over and he said he thinks it's mold

I'm located in Oklahoma