Hello, the last plasma update added the ability to change the brightness of a monitor, but I could only change the brightness of that monitor. Now, you can see the brightness of both monitors when pressing the brightness buttons, however, I need a widget if I need to change the brightness of either monitor, not a setting. So I suggest that whatever monitor has a focused window or whatever monitor you have your cursor on changes their brightness when you press the brightness button.
Or this be a setting you can enable, currently you change all your monitors brightness if you press the brightness buttons. I do thinking changing multiple monitors brightness at a time can be useful, but it should be a setting too.