These are 100% from a pest mate.
Something was munching on your plant. It happens at lights out. It must of got to that leaf early. It had a full sitting for sure.
It'll most likely die from what it did eat if you used anything with silica r pest nutrient protection nutrient.
Yes, that'll help kill anything at its next sitting if it's still alive. It'll eat, and die. Most likely is already dead.
As I said. It happens to all indoor growers. Also the Rhiz would be an attraction for it to keep eating, also the scent of the plant brings them in. Biobizz have lots you can add to it that help fend off any munchers
Nothing to be too worried about
Good luck