It was weird. I got all my Avisynth plugins from an outdated zip file that someone made.
So, I’ve updated the FFMS2 to the latest 2.22 version and I got a green upside down preview.
It was solved using the function to call just the video from the container.
I was hopping, initially, to use the AVC call command that I’ve used with ANH Silver Screen, but the AVC indexer software for the h.264 stream crashed all the time. I guess it’s not familiar with 4:2:2.