[Not my video.]
So far the FX9 footage is looking better in color, character, skintones, highlights, and overall look vs. the C500 II (ex. C300 II owner, currently shooting 1DX II (A), EOS R (B); dig Canon DSLR colors (including raw stills), lost interest in Canon Cinema color with C300 II; C500 II looks like C300 II color (though very nice improvement in real detail, slomo, raw support, smaller/lighter vs. C300 II)).
Calling shenanigans on Canon's claim of 15 stops DR. Let's see a side by side live model skin tone ramp for under/over exposure along with usable recovery in post vs. any (now ancient!) ARRI Alev.3 based camera (rated at 14 stops).
The surfing video has blown highlights in the sky, overexposed skintones, and lackluster color. Hard to say at this point if it's mostly grading, however most of the C500 II footage has this look, whereas the FX9 footage tends to pop more, and generally has been more appealing to the style I prefer: Eastman/Kodak EXR 100t 5248 film (many of your favorite films shot on this: https://shotonwhat.com/film-negative-stock/eastman-exr-100t-52487248 ). Super rich saturated colors that still look good. ARRI is very good at this kind of look too. Pushing saturation to the limit, especially skintones, and having it still look good (great!) is a challenge if the color science can't handle it. It's easy to dial back color for specific moods. Low sat looks are a great way to (try to) hide weak color science.
Note that the color options for Canon Log on the EOS R aren't very good for pushing saturation as noted above: I don't use CLog for that reason (use totally custom color via picture styles + HTP and get superior color with only a slight loss of color in the highlights (but not total DR!) vs. CLog). I prefer the color I get from the 1DX II and EOS R (with custom picture styles) vs. anything I got with the C300 II and Canon's Cinema Color (tried every option, including tweaking the color matrix): Canon's DSLR/mirrorless color science looks better for skintones in my experience. And Sony's latest color science, Venice/S.Cinetone/SLog3 is looking really impressive, especially considering where Sony was a few years ago!