Q.squash
My squash did fine the first five weeks of harvest, after that 70% of my squash is rotten on the vine. What am I doing wrong?

Are the squash just rotting on the ends? If so, this would be attributed to blossom end rot and this article can help with that: https://www.gardeningknowhow.com/edible/vegetables/squash/squash-blossom-end-rot-causes-and-treatment.htm
If the entire vine and squash are rotting, this may be an issue with vine borers. This article will help:
https://www.gardeningknowhow.com/edible/vegetables/squash/squash-pests-identifying-and-preventing-squash-vine-borer.htm