Do you see this on ALL prints, or only this one?
If you think about how the printer operates - with the build head theoretically move straight up and the projector image fixed in position - the condition you see shouldn’t be possible.
However, if the build head isn’t moving exactly straight up, if there’s any flex or movement in the XY axis, then it may be possible.
Do you have access to a good dial indicator? If you do, you could try rigging something up to measure the movement of the build head during it’s up and down stroke. I’ve done this with the build tray rotation and flex, but not with the head movement.
If there is any movement, you could try tightening all the screws and maybe the gibs just a little on the linear slide (I’m not sure how though).