Does this look like a deficiency?

Just don't listen to those who ask you to feed the plant. The leaf is overloaded with nutrients on the left side of the plant, and I would check the pH and EC of the drainage for both plants; I'm sure you'll find a lot of interesting things there. Check the runoff values; you probably have salt buildup with a drop in pH. If the drainage is too salty, then a flush + a buffer charge in the soil with fertilizers. And what about your light? It definitely looks like there's not a little; how much?

Just up the nutrients dosage slightly

Looks totally normal Around day 45, living soil plants often start to fade a bit as they redirect energy into the buds. The yellowing fan leaves at the bottom are just a natural part of the process as long as the new growth and sugar leaves stay green, you’re good. I wouldn’t worry or add anything extra, just let her finish strong

Nothing to do with oxygen.........oxygen is not a solid affected by "air intakes"!. Looks like a nitrogen deficiency and maybe a touch low on P&K also (right plant in picture).

N,P def for sure up N + 150 and P +50 ppm per liter

It's always a headscratcher when 2 plants in the same environment exhibit differently. Every plant will have its slight varying nutrient profile. But more often than not you will find some environmental metric that has slowly built up over time. The pot closest to the air intake, or air circulation has a dead spot ornot enough oxygen in a pot. Maybe one pot is fabric and one is airpot, I'd be looking at pH myself. Best of luck finding the issue.