I never understand why people prefer Vivaldi over, let's say, Chrome. I personally use FF with hardened security, but if I had no chance, I'd rather give my data to Google, not a browser company with an unknown business model and bloat.
Vivaldi is weird, I once talked with their CEO over on Mastodon (they are active there, which is a good sign, probably), it still felt shady, sadly.
The other thing with Vivaldi is I would love to keep it because of my historical love for Opera and the fact that it's their founder who started it and it's truly a passion project for him but I have never seen Vivaldi run smoothly on any machine I've ever owned (except the Android version). It's stutterry and laggy like no other browser (from what I've experienced). This has been the case for me on 3 different OSes and 4 different machines, so I'm willing to admit that I may have issues of configuration, but something else seems to be happening here (especially since other Chromium based browsers run perfectly fine, it's literallyonly Vivaldi).