Spun out of T233612

Wikibase termbox ships Minerva specific styles that impact the rendering of the page actions menu in the "AMC mode".
https://gerrit.wikimedia.org/g/mediawiki/extensions/Wikibase/+/8756168d18e574719180c45f32ffd7e10048da16/view/resources/wikibase/termbox/main.less#4

AMC mode can be enabled by visiting https://m.wikidata.org/w/index.php?title=Special:MobileOptions when logged in.

This style should either be limited to the non-AMC mode or Wikidata should consider enabling the Minerva AMC feature flags to make these the default:

"MinervaOverflowInPageActions": {
                       "base": true,
                       "beta":  true,
                       "amc": true
               },

One way this issue manifests is as strange joined buttons (the watchstar and overflow buttons act a single button in this screenshot):