Blender 5.0 got a theme overhaul, removing hundreds of options and adding some more. While versioning was attempted to keep themes looking as close as possible, some settings are impossible to guess so they require manual editing. Reset the theme to the default. Similarly to how it was done in other major overhauls (2.80, 3.0). Documentation and tools to migrate themes will be available at: https://developer.blender.org/docs/release_notes/5.0/user_interface/ Pull Request: https://projects.blender.org/blender/blender/pulls/147637