Ancient edits by logged in users incorrectly have the HTML class mw-anonuserlink on history pages.
Go to the bottom of https://sv.wikipedia.org/w/index.php?title=Sverige&dir=prev&action=history and you can see that the links to the user pages incorrectly have the HTML class mw-anonuserlink.
It's not just the HTML class, MediaWiki thinks these actually are anonymous edits:
alex@alex-laptop:~/Development/MediaWiki (master)$ ssh login.tools.wmflabs.org -t sql svwiki 'select rev_user, rev_user_text from revision where rev_id = 3309;' rev_user rev_user_text 0 Koehl Connection to login.tools.wmflabs.org closed.
This is almost certainly due to imported edits, either from Special:Import or imported manually from pre-phase3 wikis. It should be taken care of when T181731: Run maintenance/cleanupUsersWithNoId.php on all wikis is done: they'll either be attributed to a user account or will be converted into "interwiki" format (e.g. "imported>Example") if no user by that name exists in SUL.