@Terax, Floorp does support Tab Group, and for people who want both Tab Group, use Floorp, this is full guide: https://github.com/Floorp-Projects/Floorp/discussions/876
I think Mozilla devs, please consider seriously about adding Tab Group, it's a high time for us to have Tab Group because Chrome users are switching to Firefox, but the lack of Tab Group is making them go back. We can't waste another oppotunity, back...
Should be the built-in feature because after upgrading to Fission, Firefox uses a lot more memory and people are complaining about that, yeah Auto Tab Discard fixes this problem but the addon can't even unload some specific sites like addons.mozilla....