Sorry, but I couldn't think of a better description for the problem on my 2020 CX5 with 6,000 miles on it and garaged when not in use. Please see the attached photo. It LOOKS like rust, but doesn't feel like it. I doesn't wash off with any household cleaner. Appears to be some sort of corrosion.

 

Did you stick on that aftermarket stainless steel strip on bumper? I have 2022.5 model and i can only find the same item in after market accessories. I need one that has full bumper protection at ends and over the bend.

The black plastic goes to the end corners

Edge also covered.
The photos is from not sure what year cx5. I am looking for same if u find one for 2022 cx5
i just called me Mazda dealer if he had the black plastic rear bumper edge as shown, but he sent me the same photo as your stainless steel flat strip that does not cover edges. It looks like yours must be rusting so take it back under warranty and see what they say. I got top of the line everything Signature model turbo all options and did not come with this edge guard.

 

It came on my 2020 CX-5. Only thing I asked for was a loaded CX-5 with everything but the turbo engine. So it's the GT Premium package.
It may be an accessory on lower packages???? But it isn't aftermarket.

Just saw on a video that it comes with the Premium package.

 

If someone finds a link for a rear edge guard that covers edge, please let me know. I could not find one for 2022 model.
thank you