Juedge/nitta adds a MainTex texture (under Material Editor > cf_m_body) to this cards which overrides Body Overlays as far as I'm aware (the box is slightly darker when one is added)
My workaround for his cards is
ditching them when another creator uploads the character to either export his MainTex / use another MainTex with different textures, and then add the overlays to it in an image editor (though you will likely need to edit skin colours etc. if using a MainTex other than his)
Maybe there's some way to actually remove the MainTex someone else knows of because hitting
Clear or setting the scale to 0 doesn't usually work for me, but then again my Koi is a bit old and wonky lmao
It's really annoying and thankfully most other creators use overlays instead of MainTex