Astra Mini resolution of Z value

I’m capturing point clouds with Astra Mini and I noticed that Z value resolution is pretty coarse at longer distances. For example, at ~2.6m distance to a flat target, the resolution is about 28mm, i.e. I’m getting these points:

 [-123.9576   -187.60762  2682.      ]
 [-118.79163  -187.60762  2682.      ]
 [-113.625656 -187.60762  2682.      ]
 [-108.45967  -187.60762  2682.      ]
 [  51.146034 -185.649    2654.      ]
 [  56.25808  -185.649    2654.      ]
 [  61.37012  -185.649    2654.      ]
 [  66.48217  -185.649    2654.      ]

and no points with Z coordintes between 2654 and 2682. Is this normal?

Where can I find the Z resolution specifications for Orbbec 3D cameras? I need finer resolution than 28mm at 2.6m distance to target.