Hey bro, that looks like nute burn IMO, i noticed youre in flower.. what week? Have you been raising nutes, following the specific nutritional charts? Decrease in nutes late flower?

I don't think it is a deficiency. As a plant matures, it uses the food/energy it has stored in the fan leaves, which are the 1st ones to turn yellow during flowering. Some yellowing of the fan leaves should be expected, although your's looks more like a heat or Rh issue, possibly. The problem with leaves is that by the time any damage is visibly done, the true damage happened a week or two prior. There are some exceptions, such as nutrient toxicity or similar chemical burns, but by the time damage is visible, the damage is already done.
I had spider mites, which were almost invisible and only noticed it from a few light specks on some fan leaves. I treated the mites and the problem is solved, but the damage from the fan leaves is just becoming fully apparent... If I went only by leaf appearance the plants would have been dead before I had a clue as to the problem. Back to your problem... your leaves are probably showing damage from weeks ago, so they will show problems even when the problem might already be solved.
I would let the plants continue to see if the issue spreads or if new growth is affected. It's hard to diagnose things without some basic info...the type of grow, type of medium, lights, tent, etc. Some additional info is needed to help you to help yourself... keep us in the loop!

https://www.thcfarmer.com/threads/read-me-first.1245/

Will help you get the best advice.

Thank you guys so much for your responses. You guys are probably right about the burn. I don’t think I tapered off nutes when I was supposed to. My RH never goes above 52%, temps stay under 78 in a 2x2. This is my first indoor grow plus using bottled nutes. Lesson learned

That's obvious burn.