Low quality cut-scenes

[Årk Grip]

Why are they so low quality? LOL

[AortaPlatinum]

For some reason the game was promoted with pre-rendered CG versions of the cutscenes that are in the final game. If I had to guess it's because the team put together a few CG cutscenes during development but then realized they wanted to do cosmetics for Sonic, so opted to do the cutscenes in-engine instead.
If you're talking about the weird grainy effect on them... I have no clue. Same thing happens when I use the GPU-intensive cycles renderer in Blender instead of the simpler eevee renderer, so maybe the cutscenes just aren't very well optimized?