Hello Alex,
I hope you are doing well.
You have made the OnlineStatus extension, which is now unmaintained and not working well with the recent versions of the MediaWiki. Also, there are some unresolved issues on the Phabricator. (https://phabricator.wikimedia.org/tag/mediawiki-extensions-onlinestatus/)
I would like to propose archiving, as there is another alternative extension OnlineStatusBar which is working well.
Is it fine for you?
Best regards,
Zoran