Nitrogen deficiency or nitrogen toxicity or something else?

Just guessing, maybe calcium levels (to buffer effects a bit), the 2nd pic kinda shows internal pressure issues, now I dunno, but it might be overwatered (aside from nutrient imbalance) or have some root issues.

Hi Mate, first and third pics show two georgeous plants that had reached maturity .You are in a near-harvest stage, a time to flush and not to feed them anymore, stay relaxed. Second pic nutes (nitrogen) toxicity. Be balanced and all will be fine 👊

Hi mate, it looks like a bit of toxicity and lockout. Second picture definitely shows toxicity but both show problems with PH. This could be causing your lockout. I would do all the usual checks. Check your root zone for condition of roots. I hope this helps, good luck and happy growing