Yellow leaves

I kinda agree with Thraxa, looks a bit more like calcium than nitrogen to me (though, calcium can influence nitrogen uptake too, so potentially because of that it has a resulting nitrogen issue, too). The other reason why I'd rather think it's calcium is because of the overfeed sort of signs. Calcium can buffer things, balance stuff a bit and it is typically difficult to fuck up with. Excess nitrogen though is not something I'd risk with plants that are older. So I'd seriously try some calcium first. But as usual, just guessing.

Slight nitrogen defeciency, up the food 👍🌱

From the bottom up Is nitrogen as another grower has stated she needs more ':) healthy otherwise :) 👊

Looks like slight calcium defiency. If new growth is healthy I wouldn't worry about it. If not maybe add a small dose of calmag to your feed.

They are using up the nutrients in the oldest(usually biggest) leaves first. Just a natural process. You can increase your grow nutrients(Nitrogen) very slightly to correct but they look great and happy growing!!!