End of Flower, Yellow and crusty leaves ok ?

it's something you want to avoid as best you can. Sometimes senescence is impossible to avoid, but this looks more like a progression of nute-related damage. It's not a big deal, don't think it "ruined" anything or at any scale near that. It's just something you "can" improve on. Less photosynthesis = less growth or at least slow growth. So, damaging the canopy does reduce photosynthesis. the plant will survive but there's no sugar-coating it as anything but a negative impact. good news is it looks like it started back around week 10? So it is a slow progression that will only take a small adjustment to frtilizer formula, or if soil and a heavy feeder, a little extra runoff and a partial reset half way through flower, along with a slight adjustment. Did this start at the bottom initially? i can't see in your diary. If so it's probably N-deficiency, but if it started at the top it's likely something else (mobile vs immobile nute, if it starts at the top it;s more likely immobile) If that is the case, too much P or K can cause chlorosis in newer growth. you may have more than 1 nute-related issue. Those plants i back-right corner of video seem to be extra crunchy uptop.. i'd lean twoard too much p or k on thos, but the others in the front looke to have some yellow up and down the plant.. that lokos more like N-def. Diagnosis from leaf symptoms amounts to a guess with limited information to help. you can download any leaf symptom chart and compare for yourself, too.