UE - Motion Blur causes poor quality flickering dots, why?

Hello, When I start to rotate the mouse around a character in-game or start I running, jumping and moving quickly, there is a motion blur effect, but it seems strange and poor quality, not smoothed, it creates little flickering dots around a character, these dots are the same color of the character and right now, I already tried to improve all my scalability settings and nothing worked … the only way I have found to fix this is to add a post process box and in the motion blur functions, reduce the “amount” to .1, but I almost lost all motion blur.

Is there a better method to improve motion blur, and how?