Yellow blotching appearing in 3 week old plant.

The lower fan leaves have started yellow blotching of one of three of my plants. All treated the same.

Environment
2x2 with AC T22@60% 2.5’
Coco +10% perlite in 4L fabric pots
Day Temp 22-24c, RH 60%, VPD 1.
Night Temps 19-20, RH 70%, VPD .7

I have just switched from Canna start to Canna AB. 250ml Water and feed daily after lights on. Fresh water EC.3 + Canna AB 1ml/L and Canna Rhizo 2ml/L Canna Cannazyme 2.5ml/L PH 5.8, EC 1. Run off 20% PH 6.7, EC 1.1

Dont grow in coco but nobody bit. Only thing I noticed is , and i don’t check mine, but if your ec is higher in runoff . Not much but doesn’t that mean she’s not eating?alot of guys will say runoff is worthless . Idk .Maybe root probs beginning 10% sounds low?

If you are open to it, I would bring your pH down to 5.6 and try to get the run-off at a lower EC than your input.