Papa_Tanswered grow question 3 years ago I read your diary. The leaves discolouration I think is due to a slight magnesium def. I would make an epsom salt foliar spray at 20-50 PPM adjusted to 6.5 PH.
Spray that onto the plant just after lights out so your plant isn’t wet under the lights and gets light burn from droplets. This should clear up your issue.
I see you’re in soil. It also maybe time to start supplementing a bit of cal mag into your feed regimen.
Hope that helps. Cheers 🤙