Question about GP11 muddy video

Hello all!

I'm new to the forum. I had the occasion to test a GoPro 11 and i had mixed feelings about the video quality.
Here it is an example of 4K footage, linear mode, medium sharpness, Protune enabled, everything cranked to the maximum values (bitrate etc).
My feelings are that (look at the 400% zoom in second part of the video) the grass fields and woods details are a little bit "under par" for what is called to be "the best video quality action camera on the market".
Hope it's me having set something wrong (but i don't think as i have an old Hero 6 and while it has lower specs, the video it always crisp and not muddy as this from GoPro 11).
Any hints about the cause of this (bad compression IMO) effect?

Video of muddy GP11 clip

Thank you for any reply,
Umberto