(system info at bottom)
After upgrade of Kubuntu 20.04 => 22.04, Logitech Marble Trackball (mouse) is:
UNABLE to:
- click-drag window by title bar
- select text by left-click and drag of mouse
- move widgets/plasmoids
- delete or overwrite text in kRunner after first use
- click and drag window's scroll bar

ABLE to:
- activate web links and all active areas in windows and modals including settings
- activate all window's actions including buttons (minimize/maximize/close), shading (double-clicking on titlebar). etc,
- scroll the page using middle-key+trackball
- scroll the page clicking in the empty space above and below the scroll bar
- click in active editable text box to position cursor
- select text only with keyboard (SHIFT+arrow-key)
- right-click menu
- double-click mouse selects text word & line at cursor location (depending on how many clicks made as expected)

Operating System: Kubuntu 22.04
KDE Plasma Version: 5.24.7
KDE Frameworks Version: 5.98.0
Qt Version: 5.15.3
Kernel Version: 5.15.0-56-generic (64-bit)
Graphics Platform: X11
Processors: 16 × AMD Ryzen 7 2700 Eight-Core Processor
Memory: 31.3 GiB of RAM
Graphics Processor: GeForce GTX 560 Ti/PCIe/SSE2

[bump]

Found the issue. Seems that 'libinput' was not installed at all and is required to allow this Logitech USB Marblemouse Trackball to work. I followed the issue here https://bugs.launchpad.net/ubuntu/+sour ... ug/1986168.

Developers may want to check if it gets installed during upgrade but, frankly, seems to be more an Ubuntu issue than KDE.