Are Amazon Packages Shipped via USPS Being Investigated?

I recently heard rumors that Amazon packages sent through USPS might be under some sort of investigation. Has anyone else noticed delays, missing packages, or received any official notices about this? I’m trying to figure out if this is a widespread issue or just an isolated case.

I also know that a few days ago, Amazon had a major issue where it was using labels that were already marked as delivered—so I’m wondering if that could be related.