Created attachment 152601 [details]
Video showing notification popup appearing for less than the selected 5 seconds (at 120Hz refresh rate)

SUMMARY
The notification popup timer seems to assume the display refresh rate is 60Hz. The higher the refresh rate, the shorter the time that the popup is displayed, without changing the timer value.

STEPS TO REPRODUCE
1. Open System Settings > Notifications
2. Observe the value of the popup timer (Popup > Hide after: [] seconds)
3. Open System Settings > Display and Monitor
4. Set refresh rate to a value above 60Hz, e.g. 120Hz
5. Send a test notification by opening a terminal and running `notify-send "test"`
6. Observe how long it takes for the popup to disappear
7. Set refresh rate back to 60Hz
8. `notify-send "test"` again
9. Observe how long it takes for the popup to disappear

OBSERVED RESULT
The notification popup at 120Hz disappears in half the time that it does at 60Hz (half of the value chosen in settings).

EXPECTED RESULT
The notification popup is displayed for the number of seconds chosen in Notifications settings regardless of display refresh rate.

SOFTWARE/OS VERSIONS
Linux: Kernel 5.19.7-1-MANJARO
KDE Plasma Version: 5.25.5
KDE Frameworks Version: 5.97.0
Qt Version: 5.15.5
Graphics Platform: X11

ADDITIONAL INFORMATION
Requires a monitor capable of refresh rates over 60Hz. Interestingly, there doesn't seem to be a problem for lower refresh rates (tested at 30Hz).