I started using Vivaldi instead of the ungoogled Chromium, since it uses the same rendering engine and doesn’t have all the Google stuff in it. And it’s official. I used it in the past and didn’t like it. But since I just need it as an alternative untracked browser (I mainly use Firefox) it can be ok.
Being untracked means it should be, easy going, not linked to my computer. So no logged in accounts and localization. So I’ve set Vivaldi language to en-US, but parts of the UI are still in Italian and websites still shows the italian version. How come?
Searching arouns shows that Vivaldi’s language handling is very poor. And un reliable. Years old blog posts raise the same problem, which apparently remains unfixed!
The only way to change browser’s declared Accepted Languages is to change Chrome’s internal preferences.
So open chrome://settings/language and adjust the languages as preferred.
I keep my initial consideration: I don’t like Vivaldi.
Solution found on Vivaldi’s forum.