Light yellowing veins popping

Interveinal chlorosis (yellowing between leaf veins) stems from nutrient deficiencies (iron, manganese, magnesium), often due to high soil pH making them unavailable, but also from root issues (compaction, poor drainage), pests, diseases, or herbicide damage, all hindering chlorophyll production and causing leaf yellowing while veins stay green. The specific cause depends on whether it's young or old leaves affected and other symptoms present. You should be able to have an idea of what one of these fits, quite easy to rule out pests and disease, not too hard to judge if it could be compaction or poor drainage. Because its all over not localized I'd guess it was antagonism or lockout. Iron is easily screwed up in oversaturated or compacted soil. Iron goes then nitrogen processing will cease. Too much nh4+ can antagonize (lockout) the other big 3 captions "Ca, MG and K". So it could be that. Or it could just be too much calcium, whatever it is its affecting magnesium. magnesium deficiency is distinctive interveinal chlorosis, when locked out a nutrient does not follow its mobility which is the tell. When a nutrient is chemically bound or otherwise unavailable to the plant, its typical translocation process is inhibited, meaning it cannot move freely to new growth areas even if it normally would.

Looking at the very edges of the leaves I'd say she's had to much nutrition. I'd also suggest just giving plain water or water with just cal mag in it. At such a young age they don't need a great deal of nutrition. Or your Ph is out slightly only enabling it to absorb a small selection of the base nutes required to grow.