I had an Antares that was very light on the back of the seat and back of the flaps. I bought it used and it was already like that. Something I've had trouble with with all 3 of the ones I've had is under the leathers getting a black gunk under them. I don't know what it is or how to get it off. I'm wondering if its my leathers. They are covered Beval leathers.
Probably what they call "bloom"...it's wax from the tanning process working it's way out, can go on for a few years. Wipes right off.
Could also be a residue of too many cleaning products. Glycerin can seal dirt and whatever INTO the leather if you don't clean it properly first. It gets to be like waxing a dirty floor. Try just cleaning it with clean, warm water and add NOTHING. Couple of drops of ammonia in that water really help loosen the gunk and are a time tested solution for cleaning leather.
Not a fan of all the $$$ saddle products with fancy labels and extensive ad campaigns.
When opportunity knocks it's wearing overalls and looks like work.