I’m having the same issue on a brand new bike with XPLR etap. The bottom 4 gears are like a metal chain dragging on concrete. The cassette was on so tight I couldn’t even get it off to reinstall & had to have 2 guys at a shop work on it to release it. I reinstalled it (they are a little tricky to thread as I had to gently back it off & back in a couple times so it didn’t wobble), but it was the same. I asked the manufacturer is this XPLR set up is just “loud”, but they didn’t indicate tell it was. It’s much louder than rival 1, force 1, & force 22. The 1x set ups were even with a mullet, & they weren’t half as loud. I’m gonna check the b again, video the noise for the manufacturer, & possibly install another identical cassette I bought out of pocket.