I had two pots of Monstera, the small one always had these spots since I got it, but I kept it since I was hoping they would stop to grow one day. Unfortunately now it seems to have spread to this large pot too, which used to be healthy and spotless. (I probably should have spaced them apart.)
Anyone knows what these are and how can I stop them from growing all over the leaves? They can be found both at the front and back. Could it be caused by some type of virus or bacterial? The plants are both right next to my south-facing window, and there is a patio out so they don't have harsh direct sunlight. I only water when the soil feels dry, every 7-10 days. I only recently started to use fertilizer, once about two weeks ago. But the spots are around for about 1-2 months for the large pot.
Any advice would be much appreciated! I googled all over the place but haven't quite seen anything like this.