On: Solaar is a Linux manager for many Logitech keyboa...

[kdmtctl]

I didn’t even check what it could be. I just got the rainbow cursor suddenly on boot, and the process name was enough to instantly uninstall the driver and search for a replacement.

[hedora → kdmtctl]

What is a rainbow cursor?

Do you mean the mac beach ball, or is it a misguided feature of the mouse?

[kdmtctl → hedora]

Beach ball, yes. I've started to call it rainbow cursor 30 years ago on air gapped Macs, and still reluctant to absorb any other names.