The last 1.28 release was .2 at the end of April, since then 16 (by my quick count) backports that went unreleased.
- https://lists.wikimedia.org/pipermail/mediawiki-announce/2017-November/000214.html EOL announcement
- https://lists.wikimedia.org/pipermail/mediawiki-l/2017-November/046943.html @Kghbln's response
https://github.com/wikimedia/mediawiki/compare/1.28.2...REL1_28 for changes between 1.28.2 release and HEAD of REL1_28 branch