Yellow leaves from the bottom

Nitrogen deficiency - 99%. May be potassium too. Increase dosage of fertilizers. https://www.growweedeasy.com/cannabis-plant-problems/nitrogen-deficiency

Calcium and magnesium dificiantcys check ph and pH of run off if all in range if is OK would suggest a cal mag supplement with your feed

You don't have a diary so I can't be terribly specific about what to do here - but you've got probably both a magnesium and calcium deficiency which is typical as plants go into flower if you don't handle that transition properly - i.e., cutting back the grow nutes, adding bloom nutes and a dose of calmag as well as a PK booster. The deficiency can be caused by either a nitrogen toxicity (can't tell - no diary) or a pH that isn't in the proper range (for soil that's between 6.0 and 6.5). If it's nitrogen, you'll have to flush because a lockout caused by nitrogen is just that - a lockout - and even if you give it a whole bottle of calmag, it won't be able to get at it. Same with a pH problem except you wouldn't have to flush, you'd just need to get it in the right range... but if you don't get the pH right, again the calmag won't be available to the plant. Good luck.