It should be possible to exit curation mode, per https://www.mediawiki.org/wiki/Page_Curation#Curation_Mode. The "X" control at the top of the Curation Bar is not visible. This used to work, but has stopped working fairly recently. I first mentioned it on Oct 9, 2018 at https://en.wikipedia.org/wiki/Wikipedia_talk:New_pages_patrol/Reviewers#recent_changes

The close button is available on the minimized curation toolbar.