You just need to compare the regular battle theme to understand what went wrong :
https://www.youtube.com/watch?v=o0LZKtKV3lI = Cacophonic, not a single melodic line that stays more than 10 seconds, one big mashup of various previous battle themes so it sounds "pokemon"-like. There is no tension since the song just SCREAM SCREAM SCREAM
https://www.youtube.com/watch?v=Cp-waxoLel8 = Focused, clear melodic line, some moments are calmer that others to enhance the mood and the tension (54seconds)
Just like the rest of the game, the SWSH battle theme sounds like pokemon but they don't know what the fuck they are doing anymore