@mathiasbroutin-4005
Please confirm if the PostGresql is on premises or it is Azure PostGresql hosted in Azure Cloud.
Please find the official document from PostgreSql on how to use the client/server certificates.
https://www.postgresql.org/docs/current/libpq-ssl.html
According to the error, the trust is not happening between the client(your machine) and the server due to the setup. If the Postgresql is on prem, please contact the PostgreSql admin who can help in fixing this issue.
Hope this information helps. Please let us know if this answers your query.
Regards
Navtej S