It happens that on laptops with Windows 10 the screen brightness changes spontaneously. It may be a thing and useful for someone, but it annoys me terribly. Moreover, the logic of this action is very strange: with the predominance of white, the brightness increases, and if there is a lot of black, it decreases, some kind of nonsense.

Turn off adaptive brightness in Windows 10

You need to open the power settings, to do this, right-click on the "Start" menu and select "Power Options"

Opposite the current scheme, click "Setting the power plan"

Also, the brightness can change itself when connected to the network or when powered by a battery and the charge drops to the indicated level. The screenshot shows that the value in the reduced brightness mode is set to 50%. We put 100% everywhere.

Problem with Intel graphics cards

If your laptop has a built-in Intel 4000/530 or other video adapter, and the first method did not help, then do the following. Right-click on the desktop and select "Graphics Features"

The Intel HD Graphics Driver Control Panel opens. If this is not the case, then in the search bar of the Start menu, write "intel" and select "Intel(R) Graphics and Media" in the results.

In the driver panel, select "Power Options":

The second option is to turn off "Extended battery life for gaming applications". Surprisingly, this can affect the floating brightness on the desktop.

If nothing helped

If you do not play 3D games, then you can go to the extreme measure - change the video card driver to the built-in Windows one. The method is NOT only suitable for Intel.

Device Manager (right-click on the Start menu), item "Display adapters". Here you will have Intel, AMD or whatever. Right-click on the adapter and "Update Drivers..."

In the window that appears, click "Search for drivers on this computer", then "Select a driver from the list of already installed drivers"

In the list, select "Basic video adapter (Microsoft)"

The screen may flicker while changing the driver. The laptop will not restart automatically, but it is better to do it manually. In such a simple way, we turned off all the "chips" from the manufacturer, but also lost the technological advantages. In fact, now the video card can only draw the desktop and video.

To return everything back, you need to do the same, but select the old driver in the last step. Or to a system restore point.