I think some programs use xterm, so I don't want to uninstall it, but I use bash and Konsole for my terminal, so I don't need it bound to a key, especially Ctrl+f as it makes performing searches extremely annoying. The weird thing is it isn't listed in Global Shortcuts or Custom shortcuts. In Standard Shortcuts Ctrl+f appears to be bound to "find" which I think is the desired behaviour, yet every time I press Ctrl+f it fails to start the find operation and opens xterm. I am running KDE on Manjaro, and can provide a debug/log if you tell me what to do/where to find it.
Check to see if
~/.xbindkeysrc exists and has a reference to Ctrl+F.
Key binds in that file are independent from the window manager and desktop environment, and will take precedence.