The window opens on Macs whose Metal compiler rejects the shader language version wgpu takes from the macOS version: a patched wgpu-hal 30.0.1 (identical to the released crate except for this probe) compiles a tiny kernel with each version up to the OS's and keeps the first one accepted. A lost device on a Mac no longer points at the Windows-only software renderer setting (fixes#742).
Fábio Soares