Apparently Walmart and Target stay away from AWS but most of it seems to be FUD regarding, I guess, Amazon potentially targeting their competitors and their suppliers to steal data stored in AWS/use it for strategic business moves. It would be a swift death for AWS if they were found to be doing this, though, so imo the fear is unfounded.
https://www.forbes.com/sites/andriacheng/2019/07/14/amazon-a...