As shown at Special:Version, the instance of the wiki is at 1.28.0. As MediaWiki release history says:
MediaWiki 1.28 is an obsolete release of MediaWiki. Consult the RELEASE NOTES file for the full list of changes. It was deployed on Wikimedia Foundation wikis through incremental "wmf"-branches starting May 10, 2016. The 1.28.0 stable release was released on November 28, 2016.[1] Download the latest releases or checkout the REL1_28 branch in Git to follow this release.
The LTS version of MediaWiki is 1.31, with 1.34 being stable. It should be updated
As shown at Special:Version, the instance of the wiki is at 1.28.0. As MediaWiki release history says:
The LTS version of MediaWiki is 1.31, with 1.34 being stable. It should be updated