Manifest v3 update: Vivaldi is future-proofed with its built-in functionality | Vivaldi Browser
vivaldi.com
Google is forcing an update from manifest v2 to v3. With the most important functionality built into Vivaldi, it will have a limited impact. Those running extensions not supporting v3 will be affected.

That is unfortunate...
I had an unrealistic expectation, I thought they'd be able to support Manifest v2 for a long time, or find some kind of workaround.

They say Vivaldi is future proof because of their built in adblocker, but unfortunately it is not very good...