I noticed that one needs to login on commons to be able to use the WDQS linked to SDC commons. This works when writing queries on the browser, but not when used in federated queries from other SPARQL endpoints (like Wikidata).

Having to login before using the wdqs on commons also prevent using the SDC data in the SPARQL kernel of the Jupyter server of PAWS, the Jupyter server of Wikimedia.