I hope HDR can be displayed in the preview.

[afen261]

QuickLook is really cool; it allows for quick previews of many video formats, and what's even more ingenious is that it uses media extensions—very clever. It would be even better if HDR videos could be displayed during preview; currently, only SDR is supported. Also, AV1 and VVC encoded videos cannot be previewed when using MP4.

[Marginal]

It would be even better if HDR videos could be displayed during preview; currently, only SDR is supported.

Well-formed Dolby Vision / HEVC should work fine. Please use Help → Report an Issue if you have a Dolby Vision or HEVC file that doesn't.

Other HDR should produce thumbnails, but decode is too slow to be usable for preview. This is on my to-do list. I'm looking for samples to test with if you have any links to publicly available files.

AV1 and VVC encoded videos cannot be previewed when using MP4.

Unfortunately I can't do anything about that. Consider repackaging as .mkv:
"/Applications/QuickLook Video.app/Contents/MacOS/ffmpeg" -i infile.mp4 -c copy outfile.mkv