Why do leaves get yellow and die?

Yes, I believe she's hungry and resorting to starting to use up her mobile nutrients stored in the leaf tissue. This is normal and slightly early to see it but not unheard of. A little liquid kelp is good in bloom and may help boost some n too. They still need some N during flower just don't give crazy amounts to avoid grassy flavor. or any all-purpose bloom fert should have some N as well in the right ratio. if not in flower I would say feeed some fish hydroylasate.

Looks like she didn't have enough nitrogen going into flower, usually the lower leaves will do this. Your using nutes now so it's probably something lacking a few weeks back.