Why are these problem happening when i render the video?

I am having some troubles with my rendered video from unreal engine … i rendered the exr photos and combined them in davinci … what is causing the following?

Decals flicker from the beginning until 04:00

Pixelated spots on the hands and legs of the moving stomtrooper 08:19, 09:12, 10:14 and so on …

Ist it my graphic card? my settings? AA maybe? i don#t see these problems when i view the video through the camera in the viewport.

Here is a link to my video: