Welcome to the forum and thank you for your question, @featherstar. Some users experienced issues with the new Paperpile duplicates filter, so the team has disabled the feature in the beta for now. To view and merge duplicates, please go directly to https://paperpile.com/app and the old Paperpile will load.
Please note that you still can use the old Paperpile side-by-side with the new web app to merge duplicates, access shared folders and check your payment method in Settings. You don’t need to switch back completely to the old app to do those things.