MacBook Pro display suddenly has a very faint warm/pink tint I have a MacBook Pro Touch 2017. A few days ago, I noticed that the display seems to have started to have a very faint warm/reddish tint, but I can tell the difference nonetheless. The greys aren't "cool grey" anymore, but more like "red grey", and the whites are sort of "faint pink-white".

I really started noticing this because once after startup of macOS, the display was first "cool/bright" (what I would describe as normal), but perhaps 30 seconds after entry to the OS/Desktop, the whole screen switched to the red tint. This "alteration" doesn't happen every time starting the computer, but quite regularly. When comparing the display to that of a MacBook Pro 2013, it is clearly bluer/cooler in its display. 

Note that the displays aren't calibrated beyond the factory calibration and default profiles. The issue occurs regardless of any external displays being connected. This is not related to True Tone, Night Shift or anything like that.
Old answer, provided as background
I handed in my computer with the problem to an authorized service partner. At first they didn't recognize the error, but after some further convincing from my part they claim to have spoken with Apple about it.
The authorized service partner claimed that the problem with warm hue is a software bug introduced in one of most recent versions of MacOS High Sierra (spring 2018), and it afflicts various Mac models. They claim that Apple is aware of the problem, and a fix will applied in an upcoming MacOS patch.
Edit, May 2021
As of MacOS Big Sur 11.2.3 (2021-05-04), Apple haven't applied a fix, as the problem persists.
Upon multiple further contacts with Apple, it has become clear that Apple's support are not aware of this issue. They have asked for video evidence when the issue occurs. I would encourage users who experience this issue to contact Apple and send video evidence to get the issue noted.
Since Apple isn't recognizing this issue, I have unmarked my answer as a solution.