is it black mold?

its gotta be some kind of fungus?

I don't recognize the problem but it seems like the look is pretty distinctive, with that central ring and the discolored area around it. If you think it's fungus, there are fungicides available (both foliar spray and systemic) which might alleviate the problem.

Since I only see three spots.
You might consider removing the infected leaves and throwing them into the trash bin.
Foliar fungicides tend to make spots on the leaves, especially the ones with the white powder on them. So systemic fungicides are cleaner and in some cases more effective