Custom serializer?

The docs mention you can set a custom serializer for ssr, however this api seems to have changed as there is no serializer key anymore. Is this still supported or is there another place this is defined now? on version 1.120.5 https://tanstack.com/router/v1/docs/framework/react/guide/ssr

SSR | TanStack Router React Docs

Server Side Rendering (SSR) is the process of rendering a component on the server and sending the HTML markup to the client. The client then hydrates the markup into a fully interactive component. The...