Modifying the Sanity logo on the backend in v3 and finding a GitHub example.

import StudioLogo from './components/StudioLogo';
export default defineConfig({
  icon: StudioLogo,
  name: 'my-project',
  title: 'My project',
  projectId: process.env.SANITY_STUDIO_PROJECT_ID,
  dataset: process.env.SANITY_STUDIO_DATASET,
});

const StudioLogo = (props: any) => (
  <svg xmlns="<http://www.w3.org/2000/svg>" width={25} height={25} {...props}>
     Insert SVG-contents here
  </svg>
);