I find that increasing the magnification on a variable scope tends to make the focal point of the optical plane smaller than it would be at lower magnifications. Being off center on the optical plane would cause movement in your POI.
I realized, when I was teaching my grandkids to shoot, that I had to reduce the magnification when they first started to shoot because they couldn't find the image on higher power (24X).
As they go accustomed to the scope, I gradually raised the magnification. They had little trouble with finding the image once they were already in the right position relative to the scope.
Now many years later, I have found that on lower magnifications, you can barely tell you are in the center of the optical plane but being off the center will move the POI because your eye is at an angle to the reticle.
On high magnification, the optical plane focal plane is smaller,
but you can still set up slightly off center.
One thing you can do to determine if you are causing the problem is to lean your head back slightly until you see the black ring around the periphery of the scope image. If it is concentric and equal around the image, you are in or very close to the optical plane focal point. If the ring is not equally spaced, you should move your head until it becomes equally spaced and then move your head forward until the ring just disappears. If you get too close to the eyepiece, you will find that your POI will rise above your point of aim.
The second thing is to set up on your point of aim and close your eye for a few seconds. When you open your eye, check to see if your POA has moved. If it has, you probably were muscling the rifle a bit. Move your body not your head until you do not see any difference before and after you close your eye.
Either case, being off center of the optical plane or aiming at a point that is not your true aim point, will move your POI. It may not be scope parallax, just being off center on your scope's optical plane.