Highly recommend Zen Browser: https://github.com/zen-browser

What do you like about it?

its got stronger privacy out of the box than stock firefox, modern design, big fan of vertical tabs myself and it now has basic tab folders if enabled by flags. ubo/bpc both work nicely.

Vertical tabs and tab groups (I suspect it can't be that different from folders but I could be wrong) are available in Firefox.

And they're really good. I'm so glad I've discovered this paradigm.

I use a vertical task bar on KDE and a vertical task bar on Windows at work. It's such a huge productivity boost. First, I can see WAY more window previews at one time than before. And second, I can use text to tell the windows apart. 5 Excel workbooks open? No problem, they each have a name. No more clicking on one icon and then squinting at window previews to see which one you need.

…yet another Chromium browser though - supporting the Google browser monopoly.

It is based on Firefox…

They really should be a LOT clearer about it on their homepage, 99.99% of "original" browsers tend to be a wrapper around Chromium.

And as someone who actually lived through the "IE is the standard, deal with it" - age, I refuse to use any Chromium based browser out of principle. We need more actually viable engines in use or Google will just keep dictating what's allowed on the internet by the fact that Chrome has something like 90% market share on desktop browsers.