I am in 8th week of flowering. But closer to the end, more problems occur. At the beginning these were only brown spots on leaves, but now leaves also start to curve like from heat stress. This problem is for two from six plants so not sure about heat stress. pH in soil is good.
Heat stress will do it for sure (tacoing) it also looks like a classic symptoms of a calcium and magnesium deficiency (calmag or epsom should fix) but your close to harvest that I see (2 weeks, I doubt more) so I would leave it, but wait for more advise. (more eyes is always better)