@Kernal Amazing - thank you for posting this! I'm replacing all of my calipers/pads/hoses and encountered this issue with the right rear hose as well. The problem for me occurred when trying to remove the hard-line nut from the hose; I got...
I can’t tell from the video, but check out the thread below and see if this matches your observations:
https://forum.ih8mud.com/threads/engine-rattle-investigation.1315425/