The plant has now progressed to this point where t...

Nährstoffmangel wäre es bei diesen gelben Blättern, wenn die unteren, alten Blätter zuerst gelb werden würden. Da die an den Spitzen sogar zuerst verbrennen, würde ich auf zu viel N tippen. Eventuell in Kombination mit einem falschen Gießrythmus.

Underfed plant. try not to exaggerate in order to compensate but do feed a bit more than usually instructed

My plants did this same thing about week 6 of flowering. It was a lack of nutrient issue. I now know I should have started adding a nutrient line or pk booster soon after my light flip. My soil started off hot so I thought it would make it but lesson learned. I still had some fire 🔥 bud though!! Good luck 👊🏻

Nothing to do with pollination or not pollinated, she is starving for potassium and/or phosphorous. What is showing now in the leaves is a direct reflection of what was occurring in the root zone 2 weeks ago, so anything you try to do and "fix" this issue will take 10-14 days before results appear noticable in the leaves. You will need to add a P/K booster to your feding line up and yes, there are organic, fast acting liquid options out there to purchase, but again, results will take time to show, but once you start giving the P/K booster, symptoms should slow, stabalize, then show recovery in so much as the new growth won't be afected. The older damaged leaves will not recover at all unfortunately. I would leave the yellow leaves on and only remove them once they are nearly brown, this way your plant can continue to grow her flowers with some limited access to the stored P and K in her leaves.. What is happening is that your plant is "robbing" P andK from the older leaves to use for bud formatiion since there is not enough in the root zone, often referred to as the plant "cannabilizing" itself and this is why the older leaves go yellow and look sick. (just as well you did not defoliate, as then your plant would have absolutely no access to P and K and your buds would be suffering even more!) It is not a cal/mag issue, just that cannabis needs a lot of potassium and moderate amounts of extra phosphorous when flowering. Next time you grow, start with a P/K booster from about the second week of flowering and you won't have this issue again (hopefully!).

Could it be roots & are use fully allowing the top to completely dry in-between waterings?

I'm going to say that you look like a pollinated plant so check for seeds in buds and male parts happy growing