My Mavic Pro was able to automatically return and land at the exact same spot where it took off from.
However my Avata 2 is always off by 2 or 3 metres.

Is it normal for Avata series or is it something wrong with my drone?
All calibrations are done and marked as green, so unlikely to be a reason, I believe.

Sounds about right. the Mavics used their bottom OA camera to take a shot for lining up to on return, theres no camera like that on the avata.  

When I manually  engaged RTH for a test it missed the center of the landing pad by ~0.5M.  Close, but not spot on.   Bit dusty or rocky where I launch from.  Future RTH  if an option will press the Lock button to override and land manually.   

Select drones offer the Precision Landing option.  It began with the Mavic Pro.  The P4 Pro, some of the Air series including the Air 3, the Mavic 3 series, the Mini 4 Pro.  They used the downward optical flow cameras to record the terrain on takeoff, then matched it on landing.  It was pretty amazing to watch it in action.  For the Avata 2 I would really not expect Precision Landing as an option due to the redesign of the optical flow cameras to the 45° angle at which they are oriented.  For the Avata 1 it may have been possible but not implemented on an FPV-style drone.

Hi there. Thank you for reaching out.  For models without the precision landing function, in an environment with a good GPS signal, the 3-meter level deviation is normal. Have a nice day.