I pulled out the bike, got the tripod and camera, and took a shot of the Cyclone GT Mk II that's currently on the bike.
As can be seen, the pulley cage is a bit out of alignment with the cassette and wheel. The derailleur hanger has been checked and tweaked before to address this sort of visible misalignment, and was clearly not the problem.




I will note that if I grab the bottom of the pulley cage, it doesn't take much force to deflect it 5 or 10mm to the right.
I'm inclined to attribute this to wear or slop in the derailleur somewhere. Or just some flex? Not sure.

Steve in Peoria