That leaf might be showing 2 mutations. If it does spread up the plant, it's a nitrogen deficiency. If the yellow stays isolated and unchanging on that single leaf, it's just "varegation."
the lower leaves looking ugly can be normal. It;s also close to touching the rim of your setup and you get all sorts of symtoms from that, typically.
Again, if that stuff doesn't progress to other leaves, i wouldn't worry too mucha bout it. If it does, looks like a potential calcium deficiency.
Based on the leaves being shaped a bit oddly and not transitioning 3-5-7+ blades does indicate a less than ideal fertilization formula. Sometimes that can be genetics, too...
I'd definitely let this progress a bit more before reacting to it. Be 100% before you start changing nutrient formulas, because it's 10x harder to undo a wrong choice.