I'm using the version 3.3.7, for 1.15.2. When I was using 3.2.4, charms used to be colored according to the potion they were crafted with, but with the latest version, they're all gray, and undistinguishable except by hovering them.

After bisecting a bit versions from 3.2.4 to 3.3.7, it seems the charms lost their colors starting from 3.3.0 (the backporting version ?), if that may help.