Valve are still updating Team Fortress 2 (TF2), and a bigger technical update is currently in the works that will bring 64bit and Vulkan support to the Linux version.
Currently, TF2 on Linux uses ToGL, Valve's original DirectX to OpenGL translation layer. Like what Valve did with their other older games, this update will instead use the vastly newer DXVK, which translates DirectX to Vulkan. Together 64bit and Vulkan support should make the game run much smoother. Eventually, the Windows version should be 64bit too.
Not only that, it's also bumping up TF2 to use the newer Steam Linux Runtime 3.0 "Sniper", making it work better on modern Linux distributions.
You can try it out right now under the "x64_linux_test" Beta branch on Steam, which is now public, but you will not be able to connect to public servers or do matchmaking. It's purely for local testing and benchmarking. On top of that the Team Fortress 2 Dedicated Server is also being updated to go along with it (Steam App ID: 232250).
Good to see more TF2 updates really are coming.
TF2 is available on Steam.