We bought our 2021 Bolt in March 2021 and love it! We are in San Diego, CA. Bolt has around 9,000 miles now. We typically use one pedal driving. We just noticed a strange sound when braking hard using the brake pedal at surface street speeds (haven't checked yet at freeway speeds.) The sound is a very noticeable rubbing noise - almost like a growling but not a scraping noise. I looked at all the rotors and they appear clean on the outside surfaces (haven't checked the inner surfaces.) The sound does not seem to be coming from one specific corner of the car. Definitely sounds abnormal. The noise is not noticeable when using the brake pedal during normal stopping (not hard braking.) Has anyone experienced this phenomenon? Any ideas or thoughts as to what is going on?