I've had my Note 9 about a year and a half. I have had to replace the back cover 3 times, now.
It will show grazing, and then will crack. This is always where the battery is located.
I have a case and screen protector, always. It is not impact related.
It is because if the heat generated.
Has anyone else had this issue?
Tom, I think I figrured out what was causing the grazing/cracking of my back cover.
I think the battery was seated incorrectly.
I bought a new battery that actually turned out to be a bad battery. But, after putting the old one back in, I am not seeing any grazing.
So, it wasn't a faulty battery, but that fact that the original battery just wasn't in there correctly, and that bottom part was too close to the cover.
And thanks, Tom, for your interest in my problem.
It's been an adventure learning how to do "surgery" on my phone.
There is an extra feeling of success when you navigate an unknown, and, not only don't break anything, but fix it!