Well I worked up the nerve to try to change the power colors manually, since I thought that'd be fine. No saving or loading, which seemed to be what caused the problem before.
Yeah, it didn't work out that way. Last time, I changed costumes 1 and 2, with saves and loads, before I noticed. This time I changed 3 through 6, carefully picking out the right bright/dark customizations and the right colors, just to look down as I finished the last costume to see my inf bleeding out again.
I recorded the whole thing and frankly may never make any costume changes on any character ever again without recording it, though yes, it does only seem to be happening on this character right now. I don't know if that's because I haven't changed any other character's costumes lately or what. After losing what turned out to be 6,040,000 inf (which you can verify in the video), I'm kinda just giving up on customization for now.
Sorry to complicate the issue. I was just enthusiastic about finishing up my character's various transformations.
Proof: