Godot Version
v4.1.2.stable.official [399c9dc39]
I found a solution for Godot error by using scale.x = -1 in Skeleton2D and AnimationPlayer.
As the parameter scale.x = -1 cannot be used directly, the solution is to simulate that parameter, for this use scale.y = -1 and set_rotation(179.07)
I am uploading this here because I did not find any forum with your solution for Skeleton2D, if this is not the right place to upload it please tell me where I should upload this solution.