Well this is not a good sign if you compare to an healty tree.
The issue could come from the soil that retain too much water combined with too much watering.
Please remove the humidity tray!
So water, let it dry (not bone dry) and then water.
For now you can scratch the bark off a small spot and see if there's live tissues under, if not its not a good sign.
The problem you might face is if a repot could help the tree it is not in correct conditions to survive the procedure.
So you will have to be really carefull with watering if the roots can still be saved.
Remove the foliage falling on the soil and make sure the soil is not saturated with water and dry between watering.
One thing you can do now is tilting the pot at an angle and let it sit for a day of 2 after watering so the water will drain from the soil.
I personally never had success with fukien tea and forgot most about them a long time ago