See T401939: Create a Wikimedia* extension for site customizations for context.
New extensions deployed to production need a WMF team to take ownership of them.
The intent with this extension is to replace WikimediaMessages (unowned), MediaWiki-extensions-WikimediaEvents (owned by Product-Analytics), MediaWiki-extensions-WikimediaMaintenance (unowned) and some code in mediawiki-config (owned by Release-Engineering-Team, maybe?).