Like so many good shows, by the time they hit the fourth season the showrunners and producers are focused on new projects and are just phoning in their notes.
For All Mankind is terribly banal now.
Every action is predictable as basic physics, the science is shoddy with a lack of the aforementioned physics, plot holes you can fly a Saturn V through, meaningless montages or ones that bang you over the head with some idea that was already in the plot, and on and on.
At the beginning of this series, there was something real beneath it all. It seemed grounded in a vast, plausible history, but now?
It's as small and cheesy as Ilya's speakeasy with its four customers.