Yesterday I got this message for the first time, the Steam connection seemed to have a little hiccup but was back within seconds after I got the message of course after tabbing out of the suddenly black screen… To me it’s borderline a no go to have this behaviour of the game if the Steam connection is lost for whatever reasons. Especially when playing solo there’s no real need of any online services except maybe the Avalanche APEX thing.
Thinking back, I had some “Lost Steam connection” notifications in earlier versions of the game but at that time at least the game didn’t get terminated with a black screen. 