Mine is damaged as well, but I think in the rear. It was noticed when I was in for service by Tesla's repair staff. I'm waiting for a part to come in for it, but I think they quoted me somewhere in the $100-200 range for the part? I can't remember at this point.
They first tried to tell me that high water could rip it (yeah, right) but then they mentioned that it could also be debris that had been run over that ripped it. I asked them if this was a common issue, but both the rep and the manager both claim that my Model 3 was the first they've seen of this particular damage. They both claimed that when they previously worked for other automaker dealerships, this was a relatively uncommon issue, but still one that can happen to any car. We ultimately came to the conclusion that it's a sacrificial part meant to protect the actually important parts of the drivetrain from damage.