x265 encoding error.

[Selur]

The ffmpeg commands are still present in the log, so it is not that you have omitted the writing of those lines in the log as I told you in my previous message, but now the ffmpeg commands do not include the parameters that specify the color, right?

Correct. Hybrid does not include the color matrix/primary/range signaling if they are not used for the output. (like in case of piping)

In case it is that, then in the avs script log there is also no problem because no parameters with 709 are included in the ffmpeg calls. So it's fine and there is no problem.

Decoding an Avisynth script hold no color matrix/primaries/transfer information when decoded.
(iirc that is not totally correct, "-f avisynth" in Avisynth does support some additional signaling (that could be set manually), but afaik that is still experimental)
Whether there is a problem depends on what you do with your script.
If you directly encode it, the encoder must be configured correctly to contain vui signaling.
If you open the script inside another script, that script might need to know the color matrix&co to do proper YUV<>RGB conversions.

But I don't know what this is.
Does that have any influence? Or does it not influence anything and it doesn't matter?

It can. When a change is made in Hybrid, it might adjust the input color matrix signaling to that change, depending on how Hybrid is configured.
=> check your settings and the configured command lines

Cu Selur