How does Amazon seller performance validate suppliers

Hi everyone,

Talked to the Amazon account health support over the phone today, trying to understand why my recent Inauthentic complaint appeal was rejected as I have presented them with a full supply chain.

The rep said that Amazon was unable to validate my supplier using their portal and neither over the internet.

Does anyone have an idea what kind of portal the Amazon seller performance team use to validate supplier?

How does various supplier get in there?