In that first picture it looks like a bunch of little dots....turn the leaf over and look really close at the bottoms, with a magnifying glass if you have one. I'm a newb but it looks like it could be bugs.
It's a random bagseed growing outside in a 5 gal bucket outdoors.
I have it on the floratrio and I'm feeding it every other day with that while alternating watering without nutes on the Opposite Day.
So I did recently spray a homemade pesticide made of water, soap, and red chiles and sprayed the leaves to rid my plant of some spider mites I saw but I see they're still there.
I'm just sad this is happening after so long of smooth growing! Any help is appreciated!