Is there a way to quickly turn off the monitor?

I have two monitors. Sometimes, like when gaming, I find the second monitor distracting and I want it off (black). If I press the off button on the monitor, KDE starts rearranging windows and can glitch everything badly, so this is not an option. Turning the brightness to zero is not convenient and does not turn the whole monitor off either.

Currently, I am doing a stupid thing: I have a script that opens MPV without a file, fullscreen, and paused. Is there a better way to do it?