we do have some Warnings from the WindowsServer. The Warning comes from PostgreSQL.
skipping "pg_statistic" --- only table or database owner can vacuum
how can we avoid the warning
I didn't know that there is any PostgreSQL included in the Sense environment (seems that I'm not up to date anymore). But then I could imagine that there are similar logics like in QlikView in that way that the user who runs the services needs to be member of certain usergroups like QlikView Administrators and if I look on your screenshot there is no membership for qliksenserepository and therefore it might lack on the proper rights.
The Sense Repository service is a PostgreSQL database.
Its program files are found under Qlik/Sense/Repository/
Sense does not use usergroup membership for rights.
Sense services use certificates for verification of internal communication.
The database service though is a pure PostgreSQL database thus it uses PostgreSQL user accounts.