Describe what you expected should happen and what did happen. Please link any large code pastes as a Github Gist
Most likely handled by gamescope on SteamOS, which is not running in a default Fedora setup.
I've modified the launch option to use gamescope but toggle magnifier is still not working.
Same problem, using:
Your system information
Please describe your issue in as much detail as possible:
Describe what you expected should happen and what did happen. Please link any large code pastes as a Github Gist
Steps for reproducing this issue: