STABLE version -- 4.3.9.248

[Admini]

the intention is the same (to help people who use a lot of tabs) but the tab groups implementation is simple (just bundle adjacent tabs with colors)
this feature from Vivaldi and for example a well known extension for Firefox call TabGroups Manager example (unfortunately now kind of dead but still functional link here) uses a second row to group tabs.

Thanks for your feedback.
We will look into this feature.