Rusty spots with brown border on leaves

Does anyone recognize this leaf issue?

Imo looks like you need to add more calmag to your feed.

Would it be possible for us to get a pic of the whole plant? Where are these symptoms occurring on the plant, the bottom, middle, top, everywhere equally?...Are you growing in soil, or doing hydroponics?...If soil, what kind of soil?...Just some basic info that will help vets around the forum better understand the problem which = they can better help you out. Right off the bat, yeah it kinda does remind me of a calcium or magnesium issue...but those are two nutrients that sort of get the blame for a lot of things, so I try not to say that they're the issue unless I'm reasonably sure.