Is chis cal mag or iron deficiency? If iron how do...

It's Nitrogen deff. In bud you don't really need to fix it as she's don't really use it anymore and will pull from leafs as needed like she is. Can add a bit of Nuits if it worries you.

No way of knowing if it's a deficiency unless you check your runoff ph and ec levels to make sure everything is in check, and it's not lockout creating the problem. Checking your runoff ph keeps you in the know and not guessing. To add iron simply put ice cubes in your water or planter and let melt. Their high in iron. Cheers friend

Like if it was iron def., than the new leaves would be yellow

Looks like mag def. to me