I think they wanted to make her look like a cat. Like how some black cats have bits of white on them but I'm grasping at straws as to why myself.>>103810317
Most of the Jackie Chan Batman designs were bad but I kind of allow them because it was it's own show and not a big difference from one season to another like the BTAS was or even Jale Long. The only good to okay things that happened with the redesigns were Scarecrow got a design upgrade and they didn't do anything with Harley. Seeing as how they fucked everything else up I wonder how they would have redesigned her if they didn't create her themselves to begin with. They also changed characters motivation and sometimes powers, like how Mr Freeze was a guy in a cooling suit wanting to save his wife and now he's a head in a jar who just wants to be a bad dude. Clay face then became affected by electricity when that was how he faked his death in his intro.
The designs didn't get better till JLU in my opinion, but at least it had amazing voice actors throughout the animated universe.