Looking closely at your pix, do you leave standing water on the leaves like that all the time? If so, you are suffocating the stoma's. (air-gas exchange pores in the leaves) I see no nute burn on the other leaves, which leads me to believe it's likely not the MG. The olny time I spray my plants, is if I'm trying to correct a deficiency.

Let the roots uptake the moisture. That's their job. :thumbsup: