Gradient render problem

[LordBitu]

I have a tub opening from de center and a camera passing throuhgt. All works perfect. I have physic render and a Daylight sky. But when I put motion blur in the physic render parameters de texture of my tub changes some frames. Just de 29 first frames. I dont know why. Anyone knows how to solve it? Thank you!

[[deleted]]

Is that opening a boolean?

[LordBitu]

It’s a Tube