If you were a die-hard Tab Groups user, this just might be the only way forward for you with FF Quantum.

I tried many replacements for Tab Groups until this add-on came out. In my opinion, it's the only one that even comes close (unless there is a proper re-write of the original Tab Groups for FF Quantum).

There are some bumps along the way - some of them are Firefox bugs, some of them are add-on issues - but I think the developer has been doing a great job of maintaining this add-on and managing expectations.