How it is:
float g = ((color & 0x000FF000) >>> 8) / 255f;
How it should be:
float g = ((color & 0x0000FF00) >>> 8) / 255f;

this was found out recently by the dev too, should be fixed for 1.12.2 afaik or in dev atleast

I'm more curious how I (or nobody else) noticed this before, and how this didn't break all my mod colors up until now...