Clear Image Zoom - Horrible quality

[hempo22]

Hi all

was testing out the clear image zoom on the a6500 to reduce RS for some handheld but felt the quality was off.

So I did a comparison, static wide with the Sigma 30mm f1,4 and the Sony 16mm f2.8 with 2x CIZ. Both at f5,6, shot in 4k.

And the later was indeed awful, see attached snaps (SOOC). Top is 16mm+CIZ, second is 30mm.

This is not even close to the good results I've seen of others' tests online. Any setting I need to change?