I upgraded mine to FF 138. After the update it even opened the tab groups blog post. 15 minutes of going through settings later, no, my browser has no tab groups feature at all. Of course then I see it's a progressive rollout. Sad.

There is an about:config setting you can turn on. I don’t have it hear but it has been widely posted so take a look. I think if you search about:config for “tab” it might show up.