I keep researching..I am on a well, and while we have a filter (for iron and hydrogen sulfide mostly, but also general filtration) maybe the dissolved minerals are the problem. I will start watering with distilled water and see if there is improvement. The newer leaves don’t show it. Maybe it’s in the dirt? I’ll do a flush to remove minerals from the dirt too......I’m still open to other suggestions!

It probably needs to be repotted now, I bet if you take it out of the pot you'll find lots of rhizomes trying to grow, I have a plant shop and these 4" pots are almost always super root-bound.