Random crashes on vivaldi-stable, particularly not only MacOS. If it was Mac only I would not have updated to that version as it would be pointless. But yes, I doubt it will do anything for your issue.
The only thing I can suggest is close vivaldi-stable
backup ~/.config/vivaldi-stable and then delete it. Launch vivaldi-stable
it will go through the initial setup again, do not setup sync or anything just login to MotoGP and see if it works
If you get a drm / widevine issue close the browser re-launch, if it still happens goto vivaldi://components and click the button for installing / updating "Widevine Content Decryption Module" and restart the browser once more and that potential new setup issue should be fixed.
If you have the same audio issue you know its not something in your profile that has screwed up and can close vivaldi-stable
delete ~/.config/vivaldi-stable and restore your backup.
I do not have a MotoGP subscription so I can not try reproduce the issue.