hey bud, i just wanted to point out, i dont see enough air flow going on in your tent. i too have the same burning. it seems random at times kinda spoty but also burned the tips. its because of where the water pools on these plants when the lights are off. not enough air flow and it collects due and burns when the lights turn on.
rather hard one to figure out. but deff light burn. id also add more cal mag tho just being safe.
like