[IvanAchlaqullah]

Indeed. When I tried to add LibRedirect (another extensions that are not possible under Manifest v3) to Vivaldi, DNS over HTTPS suddenly stopped working.

After checking the settings page, the settings to turn it on are completely disabled. Turn out this is one of few trap in all Chromioum browser that are hardcoded by Google.

Well after searching, you need to edit registry (yikes!) and add "DnsOverHttpsMode" and set it to "safe". Problem solved, right?

NO!!! Do that and suddenly your browser wouldn't load any page at all! Turn out you also need to set "DnsOverHttpsTemplates" too.

It just so happen, somehow, there is no documentation that mention this in "....Mode" help page.

Surely Google is not being evil in here, right? Right?