Ukraine
That's worrisome. within the camera view is a clear indication that the pilot's high altitude air supply has either not been fully hooked up, or the supply pipe has slipped out of it's supply manifold.
It doesn't look like the aircraft is too high such that the pilot would need oxygen at that moment. However those moments can change very quickly and that aircraft was climbing.
Here's an oldie but goody I saw before I came here.