Hi, I thought I would append to this by mentioning how to solve this with Transforms, so I made a guide on this very thing!
Tl;dr, you can achieve stable flipping in the x direction with something like the following on the root node:
if velocity.x > 0:
transform.x = Vector2(1.0, 0.0)
elif velocity.x < 0:
transform.x = Vector2(-1.0, 0.0)
Your solution works great!, but maybe you were wondering if there’s a way around having to flip along the y axis instead, but then also have to rotate it by 180 degrees, just to flip along the x axis.