PROTON_NO_GLSL
PROTON_NO_GLSL appears in 4 issue threads across the Proton, DXVK, vkd3d-proton and Steam trackers. The values people posted, and the games they posted them for, are listed below.
__GL_SHADER_DISK_CACHE
__GL_THREADED_OPTIMIZATION
PROTON_ENABLE_NVAPI
VSYNC
PROTON_NO_ESYNC
DXVK_ASYNC
VK_ICD_FILENAMES
WINEFSYNC
PROTON_NO_FSYNC
ENABLE_VKBASALT
PROTON_LOG