At some point “unintended side effects” becomes “predictable outcomes”.
The only reliable way to get this sort of information is to ask. You cannot just extend the “open door” invitation, lean back in your executive chair, and think that you’ve done all you can.
Jeff, or a team he charges with finding facts (and not protecting egos or appearances), has to follow up on the leads, examine the stories, identify root causes, and propose sanctions and remedies. And Amazon has to be willing to accept that maybe some of its systems are producing consequences it does not desire, and that they should change.