This is a strange problem as I don't know if it's a rendering issue, a codec/decoding issue, or just the nature of the Raspberry Pi.
I'm using a Raspberry Pi Zero to play media over SMB shares, and for the most part everything works flawlessly over Wi-Fi and Powerline Ethernet. However there is a small handful of animated shows which when played have a tiny bit of lag (at certain points the video will stop for a split second) or have severe pixelation in background colours/warping/mismatched colours/green corruption.
If I play them on my Windows PC with MPC they turn out fine, and I've another PC with a stable version of LibreELEC which also plays fine, so it's only the Pi with the problem.