Apologies for the misunderstanding.
After looking at the documentation pages you’re right - they do look different.
Blender 2.8
Blender 2.9
Blender 3.1
This might sound unbelievable, but personally I think the reason how and why is that however took those screenshots changed their gizmo size in their user preferences (as I showed above).
Me:
Additionally, gizmo sizes are based on camera distance. If you zoom in closer or farther, it will change.