It's not "Newspeak". Kubernetes is an application, it runs on an OS. You can call it "Newspeak" if you consider anything after VMs became super popular "Newspeak" (around 2010, I think?).
Bare-metal = no VMs or other virtualization involved.
It is somewhat "newspeak", as bare metal has meant "without an OS" in the embedded space for a very long time. This is just a case of two different spaces using the same term for different ideas.
Bare metal has meant "whithout a supervisor" to operations for more than a decade. It has also meant "without an emulator" to the emulation community for a really long time.
I imagine it also has some meaning for the music community.
I suspect it comes from the automotive paint industry. Sanding down to the "bare metal" for the best finish...where the primer and paint are as close to the substrate as they can be.
I did couch it with "somewhat". Though it does fit the theme of a diminished meaning for the same word, since the newer meaning is a much simpler thing to do.