Please Help ! What's going on

1 check to see if it rubs off in any way. If rh is high under the canopy it could well be fungal but unlikely. But never hurts to check. I wouldnt worry about a couple isolated blemishes of its not fungal, worry if they keep progressing or more and more arise. You are feeding lotus grow 8-4-13. With a mix of nitrogen forms. Too much nitrogen which is no longer needed, not enough phosphorous and far too much pottasium. 98% of nutrients come directly from the soil water solution. Every time you feed you need to give her a complete balanced ratio.... If you give her 8- 4-13 She will barely use any nitrogen, all those salts sit in the medium unused. She will gobble up all the P and everything she needs, whatever is left remains until you flush it out. You just keep adding 8-4-13 until the pot reaches salt capacity or the ratio skews and pH skews with it. Right now you should be feeding 1-3-2 at most very near to 0-4-3. Gotta give her whay she needs not what you want.

I had the same with my Milky-way but not that intense. To be honest i just ignored it. Somebody will have a better answer for you but i dont think its bad for your plant.