Then turn off the warning: all modern OLED monitors that do not force you to run it can both change when the timer fires, but also just disable the notification altogether.
This is what I have done on mine, and mine as well also runs it when its off.
If your monitor is a Samsung OLED panel, yours is a near identical sibling of mine.
But it automatically runs when it's turned off. The warning is shown because I interrupted it running early.
The warning, for my purposes, is completely useless, and only an annoyance. The automatic feature is more than enough, and I don't need to know if it was aborted early.