Older leafs getting yellow but not spreading to other leafs..

I would not worry, those are older fan leaves. Completely normal. Just defoliate yellowing leaves. If you see the younger Fan leaves on top, then I’d trouble shoot for deficiencies. Usually nitrogen is the culprit for yellowing inflowering. You reduce the amount of N given during flowering. Not completely but significantly. Which effects leaf coloring especially if you completely cut plant off.

Hello Getting some yellowing leaves through flowering is normal, you just don't want to lose too many too fast. Sometimes if the plant isn't drinking much that can be signs of other problems like root stresses, root bound, rot, lack of oxygen, chronic underwatering, all of these can also cause yellowing leaves. Sometimes a low nitrogen level will start to yellow off leaves slowly just a few at a time but continues to lose them. Make sure the plants not being underwatered, its still getting some nutrients that contain a low N , and if the plant starts to slow in growth etc consider root problems, you can water with a hydrogen peroxide water to helps boost the oxygen at the roots but that is a short fix. Keep watching and trying that work for you and hopefully the yellowing will slow down.

Yes. I missed this diary but am keeping an updated one for the 2 new plants I have. :) Which nutrients is missing?

Привет, друг! 👋😇 Ты не ведешь дневник и очень тяжело точно определить чего ей может не хватать, но если рассмотреть твой случай в общих чертах, то ничего страшного тут не происходит! Растение уже цветёт и демонстрирует небольшой дефицит элементов в нижних уровнях, что естественно для растения в его стадии развития! 😇👌 не переставай ухаживать за своими растениями и будь внимательным, бро! Я бы советовал вести подробный дневник, тогда в случае проблем, можно было бы точнее определить причины и установить диагноз. Удачи, друг! 😇👍