Display brightness dimed on bootcamp

Hi, I have the latest version of Windows 10 installed on my 27” iMac 5K 2017. I have the bootcamp drivers all up to date. I have disabled the auto screen brightness on windows settings, but I have this problem: even if I set the brightness to 100% on windows, the maximum brightness is dimmed in comparison with the maximum screen brightness on macOS. As I said, I have disabled the auto screen brightness on windows settings. Anyone knows how to achieve the actual maximum display brightness on windows on my iMac??