I recently got the aforementioned mat from crutchfield to replace the wool rega mat on my RP6.
After putting it on and spinning several records I finally got to a colored one and noticed all of this rubber debris left behind as I flipped the record over.
I take great pride in the cleanliness of my records, and was sure this wasn’t there before putting it on the platter, but to be extra sure I let it spin a bit then checked the other side. Sure enough there was now rubber bits there too. Tried wiping the mat down with a damp cloth and they’re still popping up.
My dry brush is doing little to remove it. Hopefully I can reclean my records without causing further damage.
tl;dr: this over-priced platter mat leaves behind a rubber debris/residue that is hard to remove. Avoid.