How do I animate a Vertex Paint Brush? Is this a bug? I'm trying to animate a vertex weight paint brush (a torus object), but the animation behavior, when I keyframe the scale, is different from the viewport behavior. Here are a couple gifs illustrating the problem:

Viewport:



Keyframed:



Does anyone know how I can "fix" this and obtain the same behavior when I keyframe this scaling animation?
By configuring the "fade" setting (in the surface object), it's possible to obtain the same effect, or something close to it.