It is more clear as OnePlus introduced Zen Mode with the 7-series and has been gradually improving it since. The biggest new feature is that you can now create a virtual room and invite friends you in a focus challenge.
Anyway, the new version of the app also lets you set different themes to help your meditation experience. Also, you can record “Zen moments” throughout the day and review them later.
Note that these changes to the app is part of OnePlus’ work on the Android 11 update for its phones, but you can experience it early while still running Android 10. The update will come through the Google Play Store – here’s the page for the Zen Mode app.