One of the worst bilingual experiences is clicking “English” on a detail page and landing on the homepage.
That means the switcher behaves like a site entry point instead of a content-level language toggle. For a publishing site, those are very different things.
A better model treats language as part of the current reading state. The path stays stable while the content version changes, and related links inherit that same context.
That way readers do not have to re-orient themselves every time they switch.