What is this from?

It's only on a few leaves, but I really want to know what caused this. It's on the leaves that are located in the middle of the plant, and like I said it's only on probably 5 leaves on 2 different plants, out of 6 plants.

Been pH'ing the water between 6.3 - 6.8 and I'm using FF nutrients.

View attachment 1236543View attachment 1236544

View attachment 1236545

Thanks for the help.

That looks like you splashed some nutes on the leaves, nice looking plants btw.

Nute splash

You guys are awesome. I would have never thought of that. Guess I have to be more careful haha!