My light green hostas are developing beige colored patches that almost spread to the whole leaf. They are in moderate light. The hostas are planted in potting soil and not crowded with moderate sun. I don't think they are over watered. I don't see any bugs on them. Have this problem with several plants that are scattered along the driveway.
This could be sunspots or from watering from above. Most Hosta varieties do prefer a shady location so I do feel this is the reason for the leaf damage.
Here are links with growing information.