To me, that implies that it was drifting in the wind at that altitude since it had no visible means of propulsion.
I took a look at Ventusky (ventusky.com) to try to get an idea of the wind speed at that altitude so that I could know whether 40 mph (64 kph) made any sense.
Ventusky gives wind information at various altitudes though I have no idea how accurate the information may be. I checked the available altitudes for one close to 40000 feet and found a listing for 12000 m (39370 feet). That's close enough for the girls we go with as the old-timers always said.
For several days before the reported shoot-down (use the day selector at the bottom of the screen to see data for each day and the slider for time of day) the reported wind speeds were in the range of 20-35 mph (32-56 kph). As they say, close enough for the girls we go with especially when you consider the likely observational error associated with estimations made from a moving jet.
The first reported sighting of that object was over Nome, Alaska and it was tracked across Alaska until the shoot-down just off the north coast in the Prudhoe Bay area or just east of it.
Backtracking along the jet stream into China, the most likely source for the object, I decided that there was probably a balloon launch facility in north-eastern China, possibly near Harbin since a launch in that city will carry an object along that general route. It was just a guess and someone in one of those twitter threads actually found a balloon launch facility to the southwest of Harbin, near Hohhot that is a much better candidate for the origination point of these objects.
Anyway. It was fun looking at all this stuff but to me, these last two cylindrical things are balloons. The question about whether the balloons serve some intelligence gathering function for the Chinese will likely be answered in the coming days.