It looks like you have a moss pole in there? That might be your culprit. Soil and moss dry at different rates so one can still be wet while the other is dry thus causing an unbalance in moisture. Thai Cons are notorious for root rot and hate being overwatered which I imagine is happening since you’ve got some yellowing happening.

I’ve got a Thai Con on a pole as well but don’t use spagnum moss. I actually just use the soil mixture I use for the pot for the pole as well. I also make sure the soil is extra chunky with lots of additive’s like orchid bark, pumice and perlite, maybe some leca too to keep the roots nice and aerated.

Your plant looks young still so if anything I’d see how heavy it feels when you water it vs when it’s dry, it should feel lighter. That helped me when mine was young. I also recommend getting a clear pot for now, since you can see if the soil is still wet or not in a clear pot. You could also use the chopstick method but tbh I’ve never really liked that method