I’m wondering if the leafs have to be yellowing ...

hey there 240sx ! You're talking about senescence, that's when the plant gets those autumn colors. Whether or not this even really happens depends on the strain and the phenotype. If the plant does have that characteristic sometimes it's held back by a nutrition rich soil. The plant thinks it has enough food to keep going basically. That's why sometimes folks flush to get the colors to show, reducing the nutrients and going plain water for two weeks or so will maybe make the senescence happen. Really depends, and it's not really a "good sign" or a "bad sign" . Hope this helps ! 🚀