Google seems to have definitively discontinued the option of video calling with groups via Hangouts. Users of that service will be automatically sent to Google Meet in a new version of the app.
The redirect is in version 36.0.340725045 of Google Hangouts for Android, Android Police writes . In that version, Google is phasing out group calling via video. Users launching the app will see a banner telling them to use Google Meet. If they want to start a group conversation, Google will automatically create a link for Meet that can be shared via chat. They can then open it in the Meet app or in the browser.
It is still possible to have a one-on-one conversation with contacts, but there is a new menu option in the app that allows users to set up a Meet call. Google already decided in 2018 to eventually discontinue Hangouts , which had long been the standard video and chat service. That should happen in 2020, but the service is still usable. Initially, the chat service would merge with Allo and Duo, but Meet now seems to be the most used chat client for the company.