What is this discoloration?

What are these light patches? Is this calmag related? Or is it something else? Tried adding a little bit of calmag a few days ago in hopes the deficiency would slow down but the newest growth still shows it

indoor grow, pH is 6.0 consistently, ppm reads about 500, and I’m 3 and a half weeks in from sprouting. I feed once a week with FF cultivation nation. The plant had slowed growth at the beginning but had been taking off the past week. Had minor issues with wind burn on the first set of true leaves but nothing serious. This one was a bit of a late bloomer. Growing Barney’s farms LSD auto .