Could this be from the test of the nuclear powered hypersonic missile that Russia is developing [0]? Those things aren't designed to 'land' no pun intended
https://en.wikipedia.org/wiki/Status-6_Oceanic_Multipurpose_...
I'd sooner expect it in the Arctic Ocean, but who knows.
Edit: Some supporting evidence from twitter: https://twitter.com/FrankBottema/status/1276930424170844162