midway through flowering and 2 of 3 are fine. Middle plant yellowing on edges of fan leaves and spotting yellow. What could it be?

first thing is check Ph and Ec of runoff and root soil if you can. Could be that it’s off and causing an unhealthy plant leaving it open to a possible conditions liked “leaf septoria“. Or could just be locked out.

Can you take a picture in normal lighting? All we can see is purple.