One would expect that HDR simply extends the PQ curve from the tonemapped SDR one. The HDR version should ideally look very similar to the SDR version in the darker parts of the image as tonemapping often don't affect shadow tones.
The HDR isn't that badly messed up, it's only the darker parts of the image that lacks contrast and makes it an eye strain in dark scene compared to SDR. Despite having great programmers and artists, it's not uncommon for people to still mess things up.