You need an account if you use sync and don't want third party or self hosted solutions. I don't think that there is nothing vague or fishy in Vivaldi, it's all very transparent. Chromium (Blink) is used by the vast majory of browsers in the web and Vivaldy, apart of beeing the only EU browser is a very small cooperative in Norway. What do you think ocurres if Vivaldi release its nique UI as OpenSource, which compañies in less a second will use it for the own browser? Chrome and EDGE and killing with this definitively the competence and a free internet, include Vivaldi.

Google dominate the internet and battle against Vivaldi and others, or buy them, like Mozilla, since several years, first with discriminatory browsersniffing, blocking the access of several sites if it detected Vivaldi in the UA. Because of this, Vivaldi was disguised by the devs as Chrome against the own interests, later introducing several tracking APIs in the Chromium base, which the Vivaldi devs stripped out (except security updates) since years, before using it for Vivaldi (Because of this the Chromium base in Vivaldi is somewhat behind (~< a month) the official Chromium version. Later Google tried it with webpage APIs (FloC, idle API and others) also skipped by V devs. Mv3 also not affect Vivaldi with the inbuild blockers, no need to have the daily battle which Gorhill has to maintan uBO up to date. For YT I've enough with the Vivaldi trackerblocker and a userscript, to have YT 100% free of ads and nags since more than 8 month.

I have been using Vivaldi for 8 years and I have seen all of Google's tricks to eliminate Vivaldi as an uncomfortable competition, especially due to von Tetzchner's activism against Google's practices and web surveillance, which together with others and the Norwegian organization of consumers has driven this GDPR in the EU.

As a user I don't care about these 5% UI proprietary scripts, but I do care about the ethics and transparency of the company with the user and this is beyond any doubt

• https://www.cbsnews.com/news/interview-opera-software-ceo-and-co-founder-jon-s-von-tetzchner/
• https://www.bleepingcomputer.com/news/google/opera-and-vivaldi-founder-believes-google-should-be-regulated/
• https://vivaldi.com/blog/letter-ban-surveillance-based-advertising/
• https://www.neowin.net/news/vivaldis-jon-von-tetzchner-calls-out-google-for-anti-competitive-bullying/
• https://vivaldi.com/blog/vivaldis-open-letter-microsoft-dma-compliance/
• https://vivaldi.com/wp-content/uploads/Vivaldi-Open-Letter-Microsoft-DMA-Comp.pdf
• https://vivaldi.com/blog/technology/vivaldi-browser-at-the-web-summit/
• https://dispatch.techlore.tech/p/reclaim-control-with-vivaldi-browser

etc.

You can't buy trust with OpenSource, the trust must be gained by the author