Hello
So that discoloration is a bit odd...yes you're gonna get some leaves dying off from age, lack of light, splashes from water etc. But I'm thinking this could be fixed up by lowering your ph by a whole point down to the 6.5 range and then bringing in some mild nutrients if you don't already have dry ingredients established.
The one leaf makes me think of a magnesium deficiency with it's discoloration happening between the veins.
But mostly I'd say fix the ph and then evaluate how the plants doing.