The bottom fan leaves are dying turning yellow then falling off there is also orange rust spots on leaf. I did get gnats from flushing, cause the soil took forever to dry but I've got rid of them since.
The spots are where the bugs ate chlorophyll out the leaves and It wasn't gnats. The bottom leaves turn yellow from having a nitrogen issue when it was younger.
Those bugs are eating the hell out of your plant. Need to get you some garlic powder, mix it with water, put it in a spray bottle and lightly spray each leaf. Garlic powder not garlic salt. Very important.