Just seen this today. That "cut" in the rear tyre is actually a manufacturing fault - had exactly the same on my RD07a Conti Escape after 7000 miles of normal road usage. It looked exactly as shown in your photo. It was picked up on an MOT test but was an advisory pass because no cords were visible. Then, at the following year's MOT the "cut" had developed right down to the cords, so failed the MOT. The manufacturing fault arises from insufficient bonding of the tread-band ends together after the tread band is applied to the tyre carcass. My tyre dealer returned it to Conti and I got a small refund. I took a risk and fitted another Conti Escape - all good after another 4000 miles.
I strongly recommend other users of the Conti Escape should check theirs regularly for this. If there's any sign of that "cut" take it back to your tyre dealer!