Firefox Desktop'sSync and main (sandwich) dropdown menus and Firefox Mobile main menu expose the email address associated with the Firefox Account being sync-ed.
This may leak user's email adress, specially when showing off your screen (e.g. screencasting).
Firefox should show user's name or alias used in Firefox Account instead of email adress, so as email is not exposed when using that menu.
Note: this issue/idea was previously addressed in prior Firefox Ideas but apparently was not migrated. This (https://www.reddit.com/r/firefox/comments/wt57w5/is_there_any_way_i_can_get_my_profile_name) Reddit post reminded me this had already been discussed.
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