I've had a similar issue from my belt in another car. (I had a wear mark on the seat, but no color from my belt)
The other one to watch out for is jeans. Our old Lexus GX470 had some blue dye from jeans on the beige leather, and nothing would take it off.
The other one to watch out for is jeans. Our old Lexus GX470 had some blue dye from jeans on the beige leather, and nothing would take it off.