Re the disappearing plane: If it crashed, or landed hard at the end of that track, someone probably should have noticed and posted on the internet by now (OTOH, there's A Lot Going On Right Now)
If they turned off the transponder and headed for some 3rd country, you'd expect them to turn it back on once in friendly / neutral airspace
https://mastodon.social/@reedmideke/113615124542356546