v71 appears to have eliminated the local disconnect/device clear feature
Usually when I disconnect a two (2) checkbox 'Disconnect Sync' box appears, which after checking removes bookmarks etc from browser. V71 is not doing this and leaves my personal info in the browser I log in to.
That was a change made for Firefox 71 in response to a Bugzilla report that was filed. There is no option for deleting browser data any longer.