As reported by @Genferei:
When doing a SPARQL query, for instance this one, the links appear to point to an http page instead of https.
- An option seems to be to install the REDIRECTOR add-on for Firefox, which can be configured like this:
In this interactive window, the last entry is autogenerated given the others. (check!)
New Wikibase instance
The same thing happens with a new wikibase instance, where it is easy to misconfigure the query system to return the wrong endpoints.