Does the paddle use move_and_collide? It sounds like the paddle is moving into the ball which will cause a deeper collision than .bounce alone can handle, it will bounce away, but still be a pixel within the wall so another collision happens thus another bounce.
Maybe you can check the dot product of the collision normal and the ball’s current velocity.
func _physics_process(delta):
var colisionInfo := move_and_collide(velocity * delta)
if colisionInfo:
var normal := colisionInfo.get_normal()
if normal.dot(velocity.normalized()) <= 0.0:
velocity = velocity.bounce(normal)
var checkBrick = colisionInfo.get_collider()