This is not a disease, not related to weather, not a phosphorous deficiency or lockout, not related to cold weather, and certainly isn't burn from the sun.
It is a virus. It's a cousin of tobacco mosaic virus. Once your plants are infected, there is no getting rid of it. It is spread easily from plant to plant by pruning or simply touching plants. You can infect your plant if you use any form of tobacco. Sucking insects will certainly spread the virus too.
The best way to minimize damage is bumping up potassium levels and silicon seems to help as well. Weekly treatments of potassium has minimized the purpling in my plants. Unfortunately, it will impact yield.