Wierd dark/black spots on new grown leaves

I pretty mich have the same on 1 plant since months. It was a mix of gnats, then root damage and overwatering from neem and fertilizers. I never haf any problem with this behave if i have some insects but i just moved and my ph here is above 9. so i would say that your soil is fxcked. Ph out of control and maybe some unrecognized gnats. These brownish coloring is Mostly from damaged and brown roots. This can only come from overwatering, false fertilizing, false ph or gnats/soil insects.

Check your soil PH and the run off PH to see should also pay attention to PPM

No fungus furtunately, just fcked up balance in the soil most likely it can be traced back to whatever you are feeding her (including pH-).