whats wrong?

Needs a little more N. Let the plant suck those leaves down before removing them. If you have to tug at all to remove it, it's too soon. they should freely fall off when the plant is done shedding that leaf. Download a leaf symptom chart. google image search (or duckduckgo) will do you good. you'll see why this particuler grow question is a simple one to have high confidence in.

Seems like she wants some calcium or mag

Good old feed and defoliate them yellow and again some fan leaf in a week or so…… start with N or even cal mag!!

Yellowing from the bottom up is typical of N deficient. Want to verify your feed and levels of macros and micros you are giving them, then go from there. something aorund 3-6-8 does me good in bloom, sometimes it need more N though as my soil life is eating up a lot of it. Cold temps can also slow down growth and make the plant weird so hopefully it was not to cold the last few nights when you noticed this. Good Luck!