This URL doesn’t auto-switch to mobile view:
https://www.mediawiki.org/w/index.php?title=Topic:Sj7sxbfshzd46w7z
but this URL does:
https://www.mediawiki.org/wiki/Topic:Sj7sxbfshzd46w7z
Both should auto-switch to the mobile view because they lead to essentially the same page.
I tried both on Chrome and on Firefox on Samsung Galaxy S5.