The #mediawiki-extensions-urlshortener is awesome, but I have already found myself annoyed at having to manually type the https:// before sharing shortened urls anywhere. I know it looks less crisp and friendly, but I would highly recommend including the https:// when shortened URLs are generated at https://meta.wikimedia.org/wiki/Special:UrlShortener, in the Wikidata query engine, and elsewhere.
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Example 1. Very happy with this shortened link, but in order to make it usable and clickable for my intended audiences, I will have to manually type https:// preceding it, in order to make the link clickable and usable by my intended audiences.
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Example 2. I created [[ w.wiki/3VR | this nice query ]] for a workshop but I have to manually type https:// in front of the shortened URL in order to make it clickable in my session notes for my workshop participants. See the irony: even to make that link clickable here on Phab I have to manually type https:// in front of it!