so today, pulled out my plants from the tent to do...

I'm glad too see that you went through this deficiency ;-) Plants are looking healthy! Keep up the great work and happy growing bro

Hey there so of coarse yellow leaves can happen for so many reasons....however a nitrogen deficiency will affect the bottom leaves until they eventually die and fall off...I see you're fairly early in flowering, were you still giving some of your veg nutes in with your watering? I believe you don't want to fully remove them until at least a week or 2 into flowering, maybe a touch longer. I think the N set will also have some stripping on some leaves as well as the yellow ones. Other reasons could be down to Root pH, Poor Watering Practices, Light Burn, Heat Stress / Cold Shock Magnesium Deficiency, Iron Deficiency, Bugs or Pests, Bud Rot(many of these I highly doubt are your problem.) I think everyone gets a few yellows here and there though and your grow looks healthy for the most part. Good luck and happy growing.

Yes but as a precaution add some cal mag

Short answer, yes its normal. As long as the new growth is not affected. Old growth not getting much light, or that hasn't quiet made the canopy can start yellowing, totally normal.. that growth will fall off by itself or you can remove it. if the new growth was affected THEN I'd say its a deficiency but its not, so you're fine. Nice looking plant other than that. Keep it up.

all perfectly. the girl went to the flowering. gradually the lower leaves will eat - this is normal 👌