Thank you for your questions and pictures.
Regarding the tomato, the damage looks similar to herbicide damage. Have any herbicides been applied around the plant or to the lawn in the general area? Have you used any grass that was treated with an herbicide as mulch?
Regarding the squash, it looks like powdery mildew. Here is some information and control recommendations for powdery mildew from the North Carolina State University Extension:https://content.ces.ncsu.edu/cucurbit-powdery-mildew