I can get behind a costume change if it's a) clear and distinct, b) motivated by the music and c) creates a narrative. To pick some recent examples: I can't remember which ice dance team it was in the last Olympic year, but there was a much-hyped costume change that mostly involved, IIRC, one skater pulling some flaps of fabric loose under her arms, which didn't do anything to advance the narrative or even, for that matter, help to make it clear that there was one.
Is this the costume change you're referring to? https://www.youtube.com/watch?v=yVETC2UPojo (at about 3:38, but start a bit earlier to see both the before and after).
If it is, a kind commentator explained it for me. She's a dancer (ballerina?) warming up before a performance; then GASP the music changes, both skaters' costume changes, and the performance begins.
It's a good thing we have commentators, because I had seen the program several times and hadn't a clue.
I believe there were two versions of the costume change, with the later one a bit more dramatic than the almost-unnoticable original.