Q: I have a houseplant that looks like it’s being eaten by something but I don’t see any insects near it or on it.
A: I can determine by the yellow “halo” around the notches that this is caused by a disease, not a creature. When insects consume a leaf the damage usually does not have a halo.
There are a lot of fungi that could cause this. Use small scissors to clip the dead spots out of the affected leaves. Dip the scissors in rubbing alcohol between cuts.
Consider taking the plant outside for the summer. Houseplants that get the light they need can usually recover from damage like this.