[[ https://gerrit.wikimedia.org/g/operations/mediawiki-config/+/a816755e12f793573a0da39d70990d7e068f35d0/wmf-config/InitialiseSettings.php#7825 | $wgVectorResponsive is only enabled on testwiki ]] and [[ https://codesearch.wmflabs.org/search/?q=VectorResponsive&i=nope&files=&repos= | doesn't appear to be used elsewhere ]]. As [[ https://gerrit.wikimedia.org/g/mediawiki/skins/Vector/+/cec2337 | the configuration was introduced about four years ago ]], it seems unlikely to suddenly become popular and is most probably a good candidate for removal.
== Precursor
[] The new Vector is seen as a worthy replacement for the flag.
== Acceptance criteria
[] All `$wgVectorResponsive` is removed from the codebase
[] All `$wgVectorResponsive` references from mediawiki-config are removed.
== QA
[] Smoke test that [[ https://en.wikipedia.beta.wmflabs.org/w/index.php?title=Dog&useskin=vector&mobileaction=toggle_view_desktop | a beta cluster page loads in Vector ]].