This might to apply to native games as well, since adding -force-opengl to TF2's launch options, even when Legacy OpenGL was already selected on the dropdown menu seems to have fixed the freezing issues other Linux players are having.
Looking at what games in my library are most affected, it seems if a game has multiple options for what graphics API to use, it's more likely to run into these post launch freezes, so this might not be entirely because of Proton.
Can anyone confirm if this only occurs when using NVIDIA GPUs, since I don't remember ever running into this problem when using Intel integrated graphics or the Steam Deck.
After additional testing, I found that I might to have to add -borderless in addition to the graphics API to the launch options to get consistent bug free game launching.
This happens to me on games that use DXVK on my laptop that has two GPUs. If I disable the second GPU in Xorg it works fine.
@BugsyReportsy I don't see how ValveSoftware/steam-for-linux#11654 has anything to do with my issue.
After months of facing issues with Proton games occasionally freezing or being unresponsive after launch, I figured out it had something to do with the rendering API not loading correctly. I believe this is the case because when I specified the API in the launch options,
-dx11or-vulkanfor example, in games that officially or unoffically supported SteamPlay, they launched without issues. Before I figured this out, the freezing post start issues occured regardless of distro, Proton version, and Proton Prefix configuration.