Can't figure it out... yellowing leaves, only on one plant. Will she make it to end of flower? Would appreciate some insight –– details in comment

Thank you immensely for your insight The8thChevron. Perhaps shes just much much hungrier for Nit. Will try and update. No reason to suspect bugs. I inspect soil. Hopefully its N even though her sister got plenty. Thank you!

Side note: she will make it to the end of flower only because she will go into hyperdrive when she senses she's dying. Your yield and final product will suffer greatly.

Really not sure why her older leaves keep yellowing. These are the new yellowing leafs from the past week. It seems to be increasing in rate of yellowing. At first I thought maybe it was nitrogen efficiency –– but I think I gave her sister nitrogen excess trying to correct it (second picture). They're different strains, but the same age, both left to grow naturally no LST, but treated the exact same way. Same waterings, same intervals, same lights, etc. rH ≈ 50 - 60% Temp ≈ 75˚ F ≈ 24˚ C Regular nute schedule from General Hydroponics Definitely not overwatering pH corrected to 6.0 - 6.2. Always PPM monitored and in good levels Had a few fungus gnats, but treated with H2O2 and added layer of sand on top Growing 20/4 light schedule with 50% organic soil, 40% coco, 10% perlite mix Lights may have been a bit too close, but not showing other signs of heat / light stress. I've referenced every deficiency chart / forum on this for weeks. Just can't figure it out. More importantly though, I'm curious if it looks like she has enough green in her to make it to the end of flowering. Looks like I have another 4ish weeks to go. Any advice / feedback would be greatly appreciated. Thank you