Confused

That looks like a nitrogen deficiency groupie. Even though I assume they are all the same strain, each seed has its own slightly different genotype. These small genetic variances may not always be enough to make the plants physiologically look much different, it can greatly alter nutrient ratio that is perfect to keep each plant in optimal health. These genetic variances within a strain can be selectively breed out over time with backcrossing etc. Try uping your nitrogen content slightly and monitor closely for the yellowing to stop progressing. Before you try this though, if you haven't already, check the run off waters pH as the nitrogen deficiency could also be due to the pH being off. There alternatively could also be a build up of nutrients in your soil which is causing a lock out of the nitrogen. You could try flushing your soil with pH's water. Good luck groupie. I will send you a helpful deficiency link I found 👍