Some windows in vscode have a green title bar and sidebar. I have no idea where it comes from. Has anyone seen this? I don't think it's a theme since it only appears in some windows. And I'm not sure if it's an extension since opening different projects with the same language doesn't always produce the effect. I could also imagine that it is OS X related. For sure, it is confusing.
Edit: The effect also persists when I disable all extensions and restart vscode.
Like @rioV8 said, opening the Workspace Settings and commenting out the block workbench.colorCustomizations
did the trick for me.