i have been working a few hours with the photoshop cc 2018 animations and i came across the following problem: if i try to tween two different frames the new one, created got a white blur on it(Grey and white rectangles) i dont know how to fix it and would be so glad if someone could help me
I suppose the obvious question is what parameters did you use in the Tween panel? If you had All Layers selected for instance, and there was a layer with content you did not realize was there, and you had Opacity checked, I guess that could look like a blur or smudge.
Select a frame that shows the blur and see which layers are turned on for that frame. Ctrl clicking that layers thumbnail to load it as a selection should indicate any unexpected pixels (providing they are more than 50% opacity).