This behavior isn't unique to KDE’s Konsole; many others share it. Since Ctrl + C performs an entirely different function in most Linux terminals/shells, Firefox’s default behavior feels out of place. It’s admittedly a niche problem, but to me, it looks like an 'alien' in the Linux world.

EDIT: Thinking about it, this is actually exactly how GNU software usually works: set a weird default behavior so that people are incentivized to figure out how the software actually works just to change it.