Please include your system information as requested at https://github.com/ValveSoftware/steam-for-linux#reporting-issues for the sake of graphical information, etc.
Does this still happen?
Closing pending confirmation that this repros.
Nothing extracted yet.
Running Team Fortress 2 at 4960x1600 resolution, taking a Steam screenshot using F12 in-game (with the overlay active) results in the attached image.
![tf2_4960_steam]()