Thanks for the question.

I believe that what you are seeing on your various perennials is leaf chlorosis. This is caused by a loss of chlorophyll in the leaf except for the leaf veins which remain green. The loss of chlorophyll in the rest of the leaf causes yellow plant pigments to be visible. A loss of chlorophyll can be due to a number of things. However since you are seeing this in a number of your plants leads me to believe that the high temperatures and intense sunlight we have been having are the most likely reasons for the cessation of chlorophyll production in the leaves of the various plants. Usually this is most obvious on the upper parts of the plant where the youngest and most vigorously growing leaves are found. They are most susceptible to chlorosis. See:

https://hort.extension.wisc.edu/articles/chlorosis/

I would suggest:

1). Keep up watering on a daily basis.

2). Consider adding some iron to your gardens. Iron is an absolute necessary nutrient for photosynthesis and the synthesis of chlorophyll. There are various ways to do this. An organic way to do this is through the addition of blood meal This is available at garden centers. Follow the application instructions on the label. Chelated iron powder is another possibility. It should also be available at garden centers. Application directions should be on its label.

https://greenupside.com/how-to-add-iron-to-garden-soil/ - :~:text=You can add chelated iron,the leaves of the plant.

https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/blood-meal-fertilizer.htm

Finally, plant chlorosis in the vast majority of cases is not fatal for plants. It really is more of a cosmetic issue.

Good Luck!!