The mobile skin MinervaNeue supports site-notices only, if the config MinervaEnableSiteNotice is enabled. This should be the case, as most wikis do not have excessive use of site notices either, as well as doesn't have massive notices that do not fit on mobile devices.
Making this the default is also required to make the entrance for site-notice based extensions (like MediaWiki-extensions-CookieWarning) easier for third-party users.
To achieve that the following things need to be done:
- Disable MinervaEnableSiteNotice on wikimedia wikis (for now, until the banners are mobile friendly as well) -> https://gerrit.wikimedia.org/r/644627
- Change default of MinervaEnableSiteNotice in skin.json to true -> https://gerrit.wikimedia.org/r/644628