This is an old issue that has been known for quite a while. Fix copied from discord:
the baby has a description problem because babies don't use the standard data (news to me too).
after line 481 of files/scripts/characters/description.gd, a new line needs to be added for feathers_and_fur. I just copied the normal entry
feathers_and_fur = '$His body is sparsely covered with [color=aqua][feathercolor] bird-like feathers[/color]. Beneath that is thick, soft [color=aqua]fur of [furcolor]',
adding a new line requires that you have a decent text editor so that the newline character is correct. although [furcolor] doesn't work because it was only added to the normal description function, it doesn't cause any errors.