Where does Unity get it's display brightness info from for HDR displays?

Unity Engine
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When it comes to things like:

HDROutputSettings.main.maxFullFrameToneMapLuminance
HDROutputSettings.main.maxToneMapLuminance
HDROutputSettings.main.paperWhiteNits

Where does Unity get this information? I presumed it was from windows, but based on tests from other displays this doesn’t seem to be the case?

Is it pulled from the icc profile or something?

For example, every tested display I’ve gotten so far returns paper white as 160nits. And on another PC windows said peak brightness was 799nits but windows said 780.