Yea, somebody in the pinned thread reporting similar issue as well.
I just googled "Castle R6" and found that the character is a black guy. So whatever cheap placeholder method Ubi used, I guess your best bet for now is to find an Icon that acts as a placeholder on Foxy's face to turn yourself into Foxy again. Otherwise your Foxy will have to stay like this.
Or perhaps use a backed up save data if you do it regularly.
This happened to me, but the opposite. I was a black guy before using an Icon, and then I equipped the Unidad Icon, and now I'm stuck as a white guy with a trucker 'stache everytime I use the Unidad Icon. And nothing reverses it. So, I've just stopped using Icons and covered up my operator from head to toe. Hopefully they'll put out a fix soon that will let us revert our character's head details.