All aircraft are very sensible to wind on ground, reminding me a lot of X-Plane...
The Extra 300 even slides sideways if you align it with the rw centreline using rudder. Looking from an outside view you'll be able o see it sliding sideways.
Tested with some other aircraft, and while they are very sensible even at a quarterly 5 to 6 knot wind, they didn't slide sideways... Probably a "bug" in the Extra contacts model ?