Plant is stressed and idk what the issue is..

In that 2nd photo especially I can see clear signs of early magnesium deficiency. I think GrowingGrannie is correct.

I recently burnt my leaves with my LED and it started by looking exactly like that. It continued slowly across the sides of the leaves more than the tips. As soon as the light was raised it was fine. Damage was mostly to the larger, older leaves but only those in direct light. But other than that your plants look fine to me, dude!

I'm seeing a couple of unrelated issues here... first, the yellow veins are asking for magnesium.... might have been locked out by too much nitrogen and it will go hand-in-hand with a calcium deficiency (which I'm NOT seeing - YET). I'd cut back slightly on any heavy nitrogen nute you're giving... or simply give her plain water for a week and the cut back on the nitrogen when you resume feeding. The second issue I'm seeing is a potential insect problem... those yellow dots here and there are indicative of something having lunch ... I would check under the leaves to see if you can see anything - and I'd get some Dr. Zymes Eliminator or some Spinosad just to have them on hand... they're both organic and can be used, if necessary, all the way through harvest - and both will kill all stages (adults, larvae, eggs) of spidermites, aphids, whiteflies, thrips ... always good to have that on hand... and you MAY need to use some on this grow... Good luck...

Are the spots only on the old growth leaves?

I don't know man they look pretty healthy to me, you have a couple small blemishes but no real color changes or nasty spots or fading, I don't know i don't really see a unhealthy plant or signs of stress really...Just keep monitoring and if something gets worse post a pic...

Not sure if u have one or heard of it .but tentbuddy is a ppfd Meter that may help if u think it maybe light related. Worth checking out if u can. Helps get u in a safe spot atleast . Best of luck!!