The pot honestly looks a little small, though it is hard to tell from the photo. When I grew kale in pots, I would use the biggest pots and planters I could find, and if I used smaller they would grow to a certain size, and then stop, and always look unhealthy and sad. Unhealthy plants are much more prone to attack by bugs.
The pots I used were probably at least 24 inches tall and 18 inches in diameter. I also used rubbermaid tubs with holes drilled in the bottom and those offered them a little more space and seemed to keep them even happier. But in either of those options, I would have kale plants live happily for years. We had these big, terrible, invasive African snails that would sometimes eat through the thick bark of their stems and kill the whole plant. That is what usually killed them eventually, not old age or anything else. Same with collards.
Your temperatures sound great for kale. I used to grow a lot of it in Hawaii, which had similar day temperatures, but warmer nights, aside from a few nights in the winter (we lived at 700-foot-elevation). Kale can handle temps in the 80s just fine, and they can also handle it quite a lot cooler. You want to make sure they have plenty of water, and the pot is large enough for them to grow to their full potential, and also to keep their
roots cool.
I'd start with a bigger pot, full of rich soil/ potting mix, and see if that helps.