Hi
@peggyo! This is a normal thing, since those leaves aren't getting enough light to produce chlorophyll, the yellowing will spread and they should fall within a few days. Don't panic, focus on the leaves that are getting light and doing photosynthesis, those bottom leaves aren't much useful anyway, they're dedicated to the lower popcorn nugs. Next time I would recommend to train your plants (more horizontally) and prune those lower nugs which are taking energy for nothing. Hope this will help, keep us updated and happy growing! 👊