[HELP] What noise is that?

[Doom83]

Is that the whole thing, or just a section of the source? (300x340 is a rather uncommon resolution)
Assuming it's the whole, it looks bitrate starved.
You will probably have to throw a strong denoisers at something like that.
Some antialiasing might also help.
Note that if you use the Vapoursynth Preview it will probably look worse than it will be in a media player, since point / nearest neighbor resizing is used in the preview (players normally use at least bilinear resizing).
BasicVSR++ + bilinear resizing to 600x680:


Cu Selur

Sorry whats the type of noise at the top on the red section, like flicker? chroma noise? Try some filter about it but maybe need to find right value..or maybe are other noise