I can’t try it currently since I’m not on or near a Win10 PC at the moment, but…
Apparently the value is stored here: HKCU\Software\Microsoft\Windows\CurrentVersion\CloudStore\Cache\DefaultAccount\$$windows.data.bluelightreduction.settings\Current
You can try deleting it, restarting PC, it should create the default config if nothing is present. Back up the value before you do of course.
/edit this guy also built a PS-cmdlet for automation.
Tested this in virtual machine.
Although night light setting didn’t actually apply in virtualbox machine (picture hasn’t changed color at all), I was able to change settings / manipulate sliders.
Deleting the key mentioned and restarting machine caused key recreation and return to default settings.
After merging the key back, settings reverted to what I set before.