History of decomissioned system

I have a decomissioned system and it seems all data is gone? I was not aware of a retention on this data and I seem I can’t find it online.
I have been a member, but I might have not been for some months. Does that cause data deletion? The system data is between 2 and 4 years old.

The system should be listed under the “Registered Systems” section of the Account settings page.

All the data should still be there.