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HandBrake properly passes through the color characteristics, but does not pass through metadata that is used by monitors/TVs to optimize how they map colors when the display does not support the full HDR color gamut.
"HDR capable TV" is really a misnomer. The TV really isn't HDR capable. I.e. It can't show the full color gamut on the display all at once. "HDR capable" means it knows how to read the metadata and optimize what colors it displays for each frame to give the best reproduction it is capable of.
So HandBrake's output is technically correct (i.e. colors are represented mathematically correctly). But since pretty much no monitor can reproduce the full HDR color gamut, the reproduction without the metadata won't be the same as the reproduction with the metadata.
Out of curiosity: is it planned for Handbrake to pass through the metadata?
"Plan" is kind of a strong word for what we do around here. It's on a wish list. I (or someone else) may find time to implement it someday. There is nobody currently working on it and no schedule for when someone might look into it.