I tried to Google what it might be but keywords "splotchy leaves" only got me cannabis growing websites. I'm on the second floor with a north facing balcony in D.C./VA. It's affecting my zinnias, sweet mint, and spinach. I have other mint plants but they don't look affected, none of my other plants look affected either (rosemary, daisy, strawberry, sunflower, lavender). It had affected my marigolds and nasturtium but then it went away.