I think this issue is one or more of two things:
- overwatering leading to fungus/virus/bacteria
Diseases have a typical growth pattern. When the plant is weakened due to the root zone being saturated with water they take advantage and start growing in areas on the older leaves. You see a light spot in the center surrounded by a halo of dead tissue. Then the dead area grows larger. I see this in the picture above.
I also see what I think is a thrip. See the picture below where I have circled what looks like an adult. The diagnosis can be confirmed by looking at the leaf with a magnifying glass or similar phone app. You should expect to see silvery trails inside the leave where the juveniles live. If the infestation is advanced you may see the nymphs who are pale walking around on the leaf. Adults are dark and the size of an exclamation mark.
If it is thrips they may have come in with the plant or may have flown from some other plant. They cannot be controlled with soap and water or neem oil as the kids live inside the leaves. I suggest:
- inspect all your plants for thrip. They like Pothos but will eat other plants too
- cutting back all the leaves that have something and dispose of in a bag right away
- putting all the plants outside for a month or (if you have warm exterior temperatures) works well
- blue sticky strips may work for you but did not for me
Thrips are really hard to get rid of and sometimes just throwing the plant out is the most effective control method.