Convert a 3D Bezier curve to 2D, easily and cleanly?

Isn’t there a “clean” way to do this in Blender 3.1? The curve looks fine until I hit the “2D” switch. But the shape was never intended to be anything but “two-dimensional.”

Working with another “legacy project …” Looking for the easiest available “current” way.

?? What ? If you don’t want it 2D then don’t hit the 2D button or just don’t model it in 3D… i don’t understand this.

I wound up just doing the (small and simple …) model over, carefully clicking “2D” from the very beginning. What puzzled me is that, when building the original curve, I never consciously used three dimensions. (Constructed from a “front” view.) Yet, when I clicked “2D” after the fact, the model “went wonkers.” Oh, well. Small and simple model. “Over and out…”