Ifff you are sure you got everything else right, look into color space / gamma tags. Latest versions of Resolve allow to provide these tags in export settings.

Ifff you are sure you got everything else right, look into color space / gamma tags. Latest versions of Resolve allow to provide these tags in export settings. Sometimes you may need to use tags different than Resolve's default to make it render with correct gamma/color in QT, vimeo etc.