Picked up a 65 APO and not really feeling it...finding that focus confirmation is quite quirky when past f8, I'll get false positive flickering along the way to actual focus, with no real idea of what is accurate unless I punch in. It does this in midday sun or darker interiors, so light on the sensor doesn't seem to be the deciding factor.
If I shoot more wide open, the behavior tightens up, but bizarre for sure. I can't replicate with my other Z APO lenses.