I’m pretty sure everything from 2016-onwards is the same frame with the same capabilities, just different videos showing off how versatile it is. They actually retired that frame this year, this is the new one: https://bostondynamics.com/blog/electric-new-era-for-atlas/
Didn’t mean to imply they hadn’t been doing anything, that’s why I used the word “frame.” There are all kinds of videos of that robot trying to do backflips and the hydraulics busting in the process or other issues which would necessitate internal upgrades. Just thought it was strange that each iteration shown up to 2016 was of a different model, then we get 6 in a row of essentially the same one.