Agree that this is most likely laser damage to the sensor.
If this is a mirrorless, realize that a weakness of the mirrorless design (or shooting a traditional DSLR in Liveview mode) leaves the sensor constantly exposed and subject to damage. You have to use the same precautions with these that you would while shooting with a camcorder which also has its sensor constantly exposed.
Rodger
EOS 1DX M3, 1DX M2, 1DX, 5DS R, M6 Mark II, 1D M2, EOS 650 (film), many lenses, XF400 video
