Canon 85mm f1.2 II infinity focus quality

It's unlikely to be defective - but it's the ONE lens that seems to show you that you need to make a Microfocus Adjustment your lens - assuming your shots aren't sharp to begin with.  It's an amazing lens so I carry it almost everywhere.  I do shoot landscapes with it as well.
.
The 85mmL lens (and the 50mmL) at f/1.2 will reveal ANY shortcomings with your camera's focus settings because the DOF is so thin.  If your camera is not calibrated perfectly (for your lens), you may need to make a Microfocus Adjustment.  The 85mmL is often mistaken for being soft or out of focus by people who have only shot with a wide DOF.... because they don't realize their camera needs a very minor calibration.
.
To test, mount your camera ON A TRIPOD and then take two identical pictures of something several feet away: Take one with the OVF and one with the Live Preview on the LCD.  Compare the two.  The one taken with the LCD (Live Preview) should be accurate.  If there's an issue with your lens, this picture will be blurred or out of focus.  Now take one with the OVF (optical viewfinder).   If it is slighjtly soft or blurred compared to the first picture, then your camera needs a Microfocus Adjustment.  Consult your manual or look at YouTube for instructions.  This lens should be sharp otherwise.  Infinity focus ought to be very reasonable at even f/2.5.  My examples are taken with an EOS 6D.
.
Your problems (according to your post) appeared to be at f/14.  I'm not certain but I would assume that minor diffraction may be on the rise at that aperture.
.
Some examples from my own EF 85mm f/1.2L below:
.

f/7.1

f/2.5

f/1.2

f/1.2

f/5.6