Left shift key outputs ±
I went and bought a new keyboard and it works fine.
I had my friend plugin my broken keyboards and they have similar behavior on his Windows 10 PC (garbage on the shift keys).
I consider this solved but I am stumped that I have two keyboards with similar failure.
I would delete this question but there are other people reporting the ± on the left shift key too so I am just going to leave this question undeleted.