HI, this is something to always be aware of: you have scaled the mesh (plane) in Object Mode!
Blender now thinks the plane is still 2 by 2 meters, but with a X scale of 2 and a Y scale of 1.
So, when insetting Blender sets in X direction the same distance as in Y direction, but because the X direction is scaled up twice as big than the Y direction, it looks ‘uneven’.
Sounds confusing, right? You’ll get used to the idea.
For now, go into Object Mode and press CTRL+A > Apply Scale.
(To avoid this, as a general rule (with exceptions!): rotate in Object Mode and Scale in Edit Mode.)
