I've had this Monstera for about two years now and I've never has this problem, I'm careful not to over/under water, it's thrived until now so I suspect sunlight is not the issue either.
I've recently had a friend's Monstera over because hers was way over watered and she wanted me to try and save it. I couldn't but mine is now starting to exhibit similar symptoms, with yellowing leaves and sort of blurry patches developing on the leaves which leads me to think it might be disease related.
At first I figured it might just be that one leaf but it's now starting to spread and I can't seem to figure out why.
I've read up quite a bit online as to what it might be and I've ruled out the most common ones that are usually linked to either over/under watering as well as those that spread from plant wounds. I've checked for spider mite webs but couldn't seem to find any.
It seem to affect leaf tissue most since some leaves still have rather green veins that can be seen despite the leaf turning yellow.
Can anyone point me to what might be affecting my Monstera so I might try and save it?