I'd be able to say more looking at the scopes ... but ... without that, just from looking at the images ... there's not enough light in the shadows to make this "clean", there's going to be noise and probably blocking artifacts with any attempt to get lighter dark areas.
In grading, to make 'dark' scenes, most movie and TV productions don't start dark. They start closer to normal in lighting and exposure, and then grade the shadows down to make it look 'dark'. As then you can hold any shadow details you want, and don't have nearly the noise and artifacts to deal with.
I've made grading tutorials for a subscription Colorist site, to show Resolve colorists how to work in Premiere when they need to do so. My "suite" is properly dark, not 'black', but pretty dark, with a proper bias light behind the reference monitor to the rear wall for visual standards.
But I can't record talking to the camera with it that dark! So ... lights, camera, action, right? And I can then grade that to look like a proper colorist suite in operation.
I figured it out! I wasn't exporting at CBR.