Leaf discoloration

Yo bro, from what you’re describing—lower leaves turning yellow from the outside in it definitely sounds like a nitrogen deficiency. In flower, plants naturally use up stored nitrogen from older leaves, but if it’s happening too early or too fast, they might not be getting enough from feeding. Since you’re at day 28, they still need some nitrogen to keep up healthy growth while focusing on bud production. I’d recommend a slight boost in nitrogen, but don’t overdo it—too much late in flower can mess with bud development. A well-balanced feed with some cal-mag could also help if there’s any secondary deficiency. You got this, just keep an eye on how they respond🌱🍀💚

Just seen your giving 24hr light, that's a no from me. Other people have other options but they need the down time for sure. Knockout down to 20 hrs, I do 19 hrs all way threw with autos but tbh do photoperiod next time you will appreciate the way flowers are supposed to work and will get a feel for it.. autos do what they want when they want, it's a watch and wipe ass kind of relationship with autos.. no good.

Your doing realky well for 1st time, like number has said below.. they need nitrogen and you should get a darker green. Keep an eye on them, don't change to many things at once . Good luck

low N Ca deficiency does not have chlorosis.