This view is getting new layouts quite frequently and this time it changed as well. There you can find a dedicated section for your opened but inactive tabs. This section can be also collapsed so you will see your active tabs easily.
Recently closed tabs view was introduced previously and can be opened separately as before.
Firefox Browser (Nightly for Developers) - Apps on Google Play
Nightly is built for testers. Help us make Firefox the best browser it can be.
