I am treating for thrips at the suggestion of the local nursery, but am not seeing much change. Normally my squash grows fast and furious, so I'm really stumped.
My Squash Leaves Have Little Yellow Spots and Are Not Growing
Certified GKH Gardening Expert
It is likely a fungus. There are several that can create those yellow spots. Treat the plant with a fungicide. I like neem oil myself as it treats both fungus and pests and is safe for people and pests. This article has more information on it: https://www.gardeningknowhow.com/plant-problems/pests/pesticides/neem-oil-uses.htm