2 of the lowest fan leaves starting to wither slowly. Why?

I follow this guide for my nutrients

The plant looks healthy overall, with a minor magnesium deficiency, which I'm working on fixing by watering with cal mag when I "plain water" as well. So it gets double the dose of cal mag.

I removed 3 leaves that seemed to be struggling in one way or another. In the big whole it's not a lot of leaves, but still want to know how to improve.

spotting looks like classic calmag deficiency, make sure the pH is good on your water and just keep giving them calmag a little at a time, should fix itself.