Whats up with this?

Anybody got any ideas whats up with these leaves? Most of the plant is happy and healthy except a few lower leaves. Im like 3 weeks into flower and it just started yesterday. Doesnt seem to be spreading yet. I've been looking for bugs and haven't seen any.

Calcium deficiency

That thought entered my mind but calcium usually starts at the top of the plant.

Potassium deficiency ... looks like typical brown , crispy inner edge.

I just battled that shit recently... bumped a straight pk boost ( beastie bloom ) and all stopped progression . Even got the “ burnt “ tip which often is mistaken for over nute.

Yea I've got a couple burned looking tips and i know its not nute burn.