Vivaldi is including its own adblock outside of the manifest system that uses many of the same blocklists that uBlock does (although at this point you have to add them manually) and hopes to get near the same functionality by the time it is pulled and Mv3 is implemented. They originally had plans to offer a Mv2 compliant area but after seeing how Mv3 was going to be implemented, they changed there plans to many users dismay.