Crooked crankset? Crank/chainring not spinning straight

This is likely not an issue that just came about, but one I've overlooked for the past year or so. When the crank (vintage Sugino Super Maxy 50.4 BCD, 170mm length) is spinning, I can see it and the chainring not spinning straight; as if the crank is closer to the frame/chainstay when at 9 o clock (if being viewed straight on) than at 3 o clock.

I thought perhaps it's not fully seated on the spindle (JIS square taper) so I removed the right arm and tried all different sides of the square taper, also making sure to crank down the bolt to make sure it's all the way in. Regardless of the orientation, it seems to behave the same. So my conclusion is that the insides of the crank arm are likely deformed since it is older, maybe because of softer aluminum plus thinner arms. Maybe the arm never sat fully on a spindle, or even in the year that I had it on, it deformed. Either way, does this sound right/possible?

I've bought a new crank to replace it (Velo Orange Grand Cru rando crank) so we'll see if it changes anything.