The top level tabs have roughly stayed the same while the visual style has been tweaked to be cleaner and the owl has been redrawn.

The Clubs feature is being A/B tested against the Leaderboards tab (and some users aren't happy about it: Petition to save Clubs)

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Duolingo

App icon change
Gamification memes
App Store screenshots
Onboarding
Create profile
Duolingo Plus
Top level tabs
Learning experience
Gamification: Badges
Change or add language
Duolingo Clubs
Asking for notiification permissions during onboarding
Gamification: Streak, Lives and Gems

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Content Screens

Setup Tab
Top Level Tabs
Top level tabs
Top level tabs