I just got a Samsung Galaxy S9 last week and since day 1 it has been applying a blue light filter even though I turned blue light filter off in the settings (Blue Light Filter turned off and also schedule turned off under Settings/Display/Blue light filter).
The blue light filter's behavior is strange. The filter turns on around 6:56 every evening and turns off around 5:56 in the morning. Sometimes when I unlock my phone the filter isn't applied and a split second later I see it get applied. Even less often I see it applied in blocks quickly filling the screen. If I turn blue light filtering on in Display settings, the affect is additive.
When I got the phone all of the applications from my previous phone, a OnePlus 3, were installed, so I supposed it could have been one of those. I went into application permissions and turned off overlay permission (Settings/Apps/Special Access/Apps that can appear on top) to everything I thought might be affecting the screen color.
What else can I look into? Is there a way to check every process that's running to see what is changing the screen color?