As of this evening, when I try to make a call on Google Hangouts using Opera, I get this, no matter what device I use:
This only happens in Opera on multiple devices. Hangouts calling works just fine on Edge & Chrome, so this is an Opera-only issue, and it happens on Opera for all devices.
I have had Opera installed for months with no recent re-installs and no known updates. Everything was fine earlier today and nothing changed to my knowledge.