The KDE Taskbar settings are set to "Always Visible" so windows pass behind it, but the mouse pointer always passes in front of it, even with this setting.
Changing the taskbar visibility to "Windows Can Cover" makes SimpleScreenRecorder behave properly. But this should not be necessary because the mouse pointer always passes in front of the taskbar in all taskbar modes.
See attached video. The mouse pointer passed in front of the taskbar while I recorded it, but as you can see, the video shows the mouse pointer behind the taskbar. https://user-images.githubusercontent.com/4689691/171058433-88ee90b1-c01d-4cda-a47d-2a6e24f2b492.mp4
The KDE Taskbar settings are set to "Always Visible" so windows pass behind it, but the mouse pointer always passes in front of it, even with this setting.
Changing the taskbar visibility to "Windows Can Cover" makes SimpleScreenRecorder behave properly. But this should not be necessary because the mouse pointer always passes in front of the taskbar in all taskbar modes.