True Tone display abruptly changing tint? Try not covering the sensor!

On various forums, one can find complaints about the True Tone display of the more recent MacBook Pro models suddenly changing tint, or the intensity of the screen flickering. Some of those forums will tell you to disable the True Tone or Night Shift feature. If you don't care about those features, it's an effective workaround, but it is kind of stupid to buy a machine with all these advanced features and then disabling them.

I have also experienced this, and found no rhyme or reason behind it—until now.
I'm pretty sure there are some other causes for this problem, including hardware or software faults, but before you go bringing your MacBook Pro to a service center, you might want to check the following first.

Many people cover the camera built into laptop screens with a sticker or something else, for reasons of privacy and/or security. The problem is that the True Tone sensor is very close to the camera. If your sticker is large enough, it will partially or fully cover the sensor. Even if that's not the case, maybe you often do use the camera, and then have to park the sticker somewhere, and a convenient place is right next to the camera—possibly right on top of the sensor.

When covered, the sensor will receive much less light than it should, possibly filtered in some strange way, and this can cause the True Tone system to react wildly to tiny changes in ambient light. I still don't understand why the adaptation algorithm allows such quick changes at all, but one can't really blame the system for starting to act weirdly in a very poorly conditioned situation.

The sensor is very hard to see, which is why most people are unaware that it exists at all, let alone avoid covering it. On my MacBook Pro model (2018 15 inch), the sensor proves to be at 17 mm to the right of the (more visible) camera, as can be seen by shining a strong flashlight across it. You may want to verify on you particular machine where the sensor really is situated.

So the morale of this story is: if you have any thingamajig that covers the camera, make sure it stays well away from the sensor. If you then still have strange variations in the tint of the display, then you may start worrying about a deeper problem. As a matter of fact, in my case the problem still occurs occasionally. It looks like the sensor gets confused in situations where there is little light, or rather weak light coming from a direction mostly parallel with the screen surface. What usually helps in such cases, is to provide a stable source of light closer to the computer, so just turn on a lamp.