It doesn't look light-related to me either, otherwise the top leaves (closer to the light) would be worse than the lowers.
Looks more like nutrient burn to me, especially the most recent pics. It can affect the upper leaves more because they're photosynthesizing/metabolizing faster due to more intense light, so the problems show up there first.
ok. thank you for all the answers. i'm a beginner, and from now on I'll take notes of everything and ask knowledgeable people. i'm cutting these out and starting a new adventure.
I don't know how much you've been feeding from the start.
But I know if you overfeeding and get s build up of nutrients through veg you won't necessarily see the detrimental effects until half way through flower, by which time its difficult to correct . Especially in soil where problems are further delayed and rectification is also delayed.
So I'd look at it as a feeding issue.
If its soil don't feed ot until it needs it then dint feed every water.
I'm not a soil guy but best practices shouldn't be hard to find and plenty of people will be using the same as you.