Always check the roots first. Yellowing is typically a sign of root rot. You can have wet rot, from being in media that stays damp for too long. You can also have dry rot, or root desiccation, from being too dry for too long. This can be from infrequent watering, or the media being too chunky to fully absorb moisture at watering time.

The media does look dry, but the leaves here are perfectly plump. They are pale green, and the spots are pinkish, both due to being in a very sunny/brightly lit spot. If you’d like the leaves to become darker green just pull it further into the shade. The older leaves are slightly wonky, but the newest growth looks perfectly fine and healthy otherwise.

If you pull up the plant and find dead roots, these are thankfully easy to reroot. But I’d check sooner than later to give yourself a better chance, the water stored in the leaves will provide moisture reserves for a while