Either armor skins have really taken off, or it looks like secondary colors are showing up in team matches (to an extent.) White shows up completely, but as for the rest it seems like they’re being forced to a pallet of warm and cool. If your secondary color was a bright color it shows up as bright blue on blue team, and pink on red team (I think.) As always though, I could be wrong. Though I liked this detail in Halo 2 and it seems much more organized here.
I think it’s just the way some armor is designed and has nothing to do with secondary colors.
Yeah I’m fairly sure these are skins.