Plant growth stunted

Hey guys, this is my second grow and this time i got some issues on here. So i have 4 plants of Sweet Skittlez same strain same batch. But they are all 4 different which i suppose is normal. I made a mistake, and didn't reduce the N when they entered in flower, so i suppose they got some nute burn. Which i acted upon and 3 times straight gave them only RO water. But the growth seems to be very slow. Especially on plants 1 and 4 (from left to right)

They are in a controlled environment with temps ranging from 21,5 (min at night) to 26,5( max during the day). Its an organic grow, with 3 100w led lamps in soil with 30% of coco.

Here is the panoramic


They are now entering the 5th week of flower, and my issue is that 1 plant in particular (number 4) is showing some heavy signs of something here i hope someone can help me out.

these marks are all over the leaves especially the older ones and i see that the buds are growing very slow. Another plant (number 1) is also having the growth stunted but the marks are different, less uniform. Pasting the most extreme one i found


here is the medium buds i currently have, id say its a bit small for the finished 4th week. At least smaller than my first grow.

I hope someone could help me and appreciate a lot any input.!

Thanks guys and cheers!!

it doesnt look like pests have you sprayed them at all with anything even water in flower?

no, i try to avoid that especially in flower. I also thought about pests but can't find any living sign of it

possible nitrogen deficiency dont quote me on that but the are very light green almost opaque

can it be calcium deficiency and nitrogen excess (as nute burn)?

hmm i think you can have a point with the leaves yellowish

final update, there were two issues if that can help anyone:
1) Nitrogen and Mag deficiency
2) Light distance, they were two far away. After lowering them the plants started to go faster, but i lost 2 - 2,5 weeks with that.

Anyway hereby is the final result, a lot of small buds (damn light), even the big buds are not so big as the previous ones. 388 gr dry weight

will do better next time