Hi @Ana_Carvalho This is the canton internal system party which is created as part of every ledger.
Here is some description on what this party is and why it is called what it is called Canton Allocates Parties Automatically? - #4 by Ratko_Veprek
Previously there were multiple endpoints that were sometimes hiding this and sometimes including it – since it is a party that is present in the system we are now always showing it so that the UI marries up to what the raw API returns.
The party does not have a display name so that is why it is showing the full literal name which is the ledgerId + unique suffix identifier of the participant.
You should not need to use this party for any of your workflows – it is automatically created by Canton and used internally by Canton.