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Mozilla Firefox is Working on a Tab Grouping Feature
(news.itsfoss.com)
A place to discuss the news and latest developments on the open-source browser Firefox
Yeah of course, but that's why all browsers - AFAIK - allow you to open new windows not just new tabs. This naturally groups tabs into contexts. In other words, this very feature is implemented already.
But in a new window i don't have the 10-20 pinned tabs that I jump to very often, having tab groups helps in this regard.