leaf green discoloration 1 week into bloom

Nitrogen deficiency; pretty easy to correct with (a little bit) of nutrition :)

Your plants need nitrogen for the first 3 weeks of flowering. So even though you switch to 12/12 or your plant starts flowering, they still need nitrogen/ grow nutrients for the stretch phase Also after that, they will beg you for calcium and magnesium for bud development. Stay on top of these things to prevent them and your plants will love it. Nitrogen for stretch and cal mag for bud development. Your plants will want this everytime

A bunch of things cause interveinal chlorosis. If spots don't show up with it, probably not Mg. Looks like it is at least somewhat mobile as i see lower leaves with the symptoms. Fe or Mn come into play, but it'd be really rare to have a trace element issue. Is pH balanced? If in soilless/hydro you need to provide trace elements - ensure one of your products have them. nute lockout is also more likely, but the plant doesn't look significantly overfed to do that. Not enough info. You'll have to eleminate possibilities. Download a "Marijuana leaf symptom chart" -- i like the one stamped with jorge cervantes name. There are some youtube vids worth watching too. Ugh, i just downloaded the video. I don't have the URL, but they purposely witheld nutrients and took pictures of each deficiency/toxicity etc... Life is sometimes mess.. it doesn't always look as 'neat' as the reference table images.

Could be iron, magnesium or nitrogen deficiency. More info on nutrient program would be helpful to determine what it may be.

Looks like a slight magnesium deficiency