Im just seeing a fade, keep an eye on it though. Lower leaves for a plant is just Mobile nutrients so the plant will always start to consume it’s lowers to give it the nutrients it needs to push it’s flowers, once they are yellow I just pluck em as they don’t benefit the plant anymore but not uncommon to see in 3-5 weeks into flower and why I usually try to make sure they get a nice heavier compost tea feeding on the last flower tea before switching to finishing tea so they got all the punch they need
Rust spots are usually a calcium which can easily be added by simply top dressing with eggshells or throw some ground oyster shell or oyster shell flower topdressed or in a tea, but can also be pH so def check that.
Also looking closer your leaf tips look lighter than the rest of the new growth leaf which also indicates a possible pH just slightly throwing uptake unavailable on something and a watering allowing uptake in the last few days.
Sometimes salt build up can cause these weird issues and if ur able to make a tea I’d get one brewing right away and then in the morning before you feed it give a nice flush out of the soil, wait 15 min to allow salts to dissolve and blast it again then feed the tea concentrated in half the amounts back into your soil. That would be the simplest solution
Went scrolling in closer again and I see a bunch of dots on the tops of ur leaves, have u looked on the bottoms of em for bugs?
