Yes, exactly that. Between the Android Browsers Flow works and synchronisation in general as well, but between PC and Android it's exactly as you describe.
I got it to work for now: after scanning the QR code and leaving it at the "follow the instructions on your device" (or something along those lines) then closing the opera app in Android's recent apps overview. When starting the app again, flow was working.
But on top of that the synchronisation between multiple PCs seems to be screwed as well. I especially notice it in the synchronised tabs: whereas each of my android devices is shown once in the tabs/devices list (as it should be) each PC shows up multiple times. At the moment some of them seem to show up around 20 times with different tabs each 🤓