Question about GP11 muddy video

I did shot other clips also on near subjects with similar results. I'm sure it's not fog related, it's light related imo.
Looks like that on low contrast details there is some kind of aggressive noise reduction and/or compression artifact.
The issue is nearly invisible on highly lit scenes, but on shadow details tends to appear. I don't know if it's something related to my unit, looks strange to me that I nearly found nothing about this on the net.
By comparing GP11 clips with my old Osmo Action 1 clips, looks like GP11 has an aggressive noise reduction algorithm while the Action 1 but also Hero 6 show details.
Really don't know how to interpretate this result.

I really want to use the GP11 for VLogging but first I need to understand how to fix that.

Umberto

It may be the case. Honestly, I always been used to manage video noise in post, to get the right spot between noise and video quality, for each clip I shot. I can understand that an action cam should be able to "bring footage home" without much hassle, but having GoPro the Prores mode, I'd expect being able to choose whether to use noise reduction or not. Sometimes I think it's better to keep some noise instead of smudged details.
Should this aggressive noise reduction algorithm always active because the camera needs to reduce details because of writing bandwidth?