The short version is, that under [[Special:Preferences#mw-prefsection-editing]] / Editor / Editing mode, it seems to remember your last editor even if you've got "Show me both editor tabs" selected.

See https://en.wikipedia.org/w/index.php?title=Wikipedia:Village_pump_(technical)&oldid=902833853#Can_no_longer_get_to_deleted_edits,_visual_editor_gets_in_the_way. for more details.