Why is the divide between PostProcessingInput0 and DifferColor flickering like this?

Hi, I’m super new to unreal engine and shading but I think I found a super-specific problem.

When adding a post-processing material like the one below:

I’m getting a very strange flicker over the entire screen, even in a blank project without any started content. I recorded a short video showcasing what is happening. Any help would be greatly appreciated!