I just switched from Windows to Fedora and on my Windows install I always used ^ to show the scoreboard in League of Legends.
When I try it on Fedora nothing happens ingame and on the lower left corner of the game (or any other program I’m in when I press the key) it shows the Caret Symbol until I press it again.
It’s a dead key, and the system is waiting for you to press another key so you’d get something like û as input. I’ve noticed this happening with ´ in MMOs where actions map to the number line on the keyboard, and the furthest-to-the-right key on that line is ´ on my keyboard; a dead key. The ´ shows up in the bottom left corner as indication that GNOME is waiting for me to press another key. I’ve never found a way to get rid of this behavior while a game is open, so I just work around it my remapping game keys to something else.