Elaborate on known issue: "Programs can behave like there is no OpenGL support when using Mesa opengl32.dll since 21.0.0"

[nealkruis]

This is not a defect but rather a behavior change of Mesa when environment variables are misconfigured. It usually happens when selecting a Mesa driver that doesn't exist in release package used or it fails to initialize due to host system not meeting hardware requirements or lacking dependencies. Reading differences between MSVC and MinGW packages and Mingw and MSVC Package contents should aid in troubleshooting.

Can someone explain in more detail the relevant parts of the "differences between MSVC and MinGW packages and Mingw and MSVC Package contents" sections?

I don't see much describing environment variables that can be misconfigured.

[pal1000]

The most common scenario for this behavior occurs when you try to explicitly select a Mesa3D OpenGL layered driver via set GALLIUM_DRIVER=d3d12 or set GALLIUM_DRIVER=zink and your system doesn't meet the respective requirements. See description for GLonD3D12 and zink in Mingw and MSVC Package contents.