It seems as though we've inherited Chrome's experimental "tab groups" feature and that it works in Brave as well without issue (seemingly). The feature still sits be hind a flag (#tab-groups) right now and I think it would be advantageous to hijack this feature and make it our own.

The way the feature is currently implemented:
Right-clicking on a tab gives you options to Add, Add to existing or Remove a tab to/from a group.

You can also drag tabs into (or out of) pre-existing groups.

If you Ctrl/Cmd + Click a link on a tab already grouped, the link will open and be automatically added to that same tab group.

Clicking the tab group color gives you options for customizing that groups color and giving each group a name/title.

Optionally/additionally, we may want to consider re-implementing the tab "pages" feature in conjunction with this, the way we did in Muon. I'm personally a fan of Cliftons "slick animation" example.
Implementing this would make many users happy -- as it has been requested several times and in many different ways. These are just the ones I've pulled from Community in my initial search:
Finally, my suggestion from browser-laptop is implemented upstream. I'd give a +1 for tab colours so helpful when you have loads of tabs opened
+1 from @jaredready via https://github.com/brave/brave-browser/issues/9419
The latest release of Chrome and Chromium supports tab groups. Is this something that Brave is planning on supporting?
https://gizmodo[dot]com/tab-groups-is-chromes-best-new-feature-in-years-and-he-1842944249
Quick testimony : I almost hesitate to switch back to Chrome to benefit from this feature that I think would bring relief to any many-tabs-worker on a daily basis (don't know if I'm the only one that eager to have it available).
The new 'Tab Groups' feature works really great in the Google Chrome browser - and really falls flat in Brave. Really hoping this feature will be properly implemented in Brave _soon_!
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Finally, my suggestion from browser-laptop is implemented upstream. I'd give a +1 for tab colours so helpful when you have loads of tabs opened