What’s going on with my plant

I noticed these little spots on one of my leaves The PH is balanced and I’ve been monotoring the ppm keeping it around 250-300 using a rockwool cube. Should I add calmag or cut nutrients as a whole for right now. Keep in mind this is a Bruce banner auto.

I noticed these little spots on one of my leaves The PH is balanced and I’ve been monotoring the ppm keeping it around 250-300 using a rockwool cube. Should I add calmag or cut nutrients as a whole for right now. Keep in mind this is a Bruce banner auto.