Is this severe Cal-Mag deficiency?

its happening in all the leaves or just a few ? maybe its just an old leave

doont mind in week 6 of flowering for some old leaves...... she is aging, and that is like they look

yes you have cal mag issues going on, so if i was you i would start using a cal mag supplement in your feed, also when you do start to use cal mag, cut the dead looking parts off your plant so you will have just healthy growing green on it instead of the damaged areas. plants like cannabis(some strains) need more cal mag in their diet. cal mag also promotes bigger bud growth ect. hope this helps