That is a wallet with a lot of Bitcoins in it. We don't know to what degree it's controlled by Tether. We don't know the degree to which it's otherwise encumbered. If I recall correctly, FTX also pointed to wallets with Bitcoins in them from time to time.

To be clear, I am not saying Tether is committing fraud. Just that to the extent there have been investigations, they came up short, and that them being short is not even among the main risks to their existence.