“Reunion episodes” have been a thing for years. Wikipedia even has a whole list of them.

Originally most of them were just getting the cast back together to talk about the show. The TV show Friends did a version of this a few years ago.

We also got the film or TV movie that revisited the cast and story, usually a few years after the show ended. The TV show Psych did a handful of these.

And of course more recently, as you noted, we’ve started to get the new seasons version. King of the Hill would be a good recent example of this format.

It’s fun to revisit the worlds these shows created. Some suck. Some are great. Some are just sorta in the middle.