On other devices like iPhone or Desktop, after logout, the language is navigator’s header language.
On android, when first access the site, language is same with the navigator.(ok)
After login, it turns into user setting language.(ok)
And if I logout, it turns into english, no matter what the navigator’s header language is. (not ok)
This is a caching issue, and supporting per-language anon users means destroying your cache, since it fragments the cache into {x} different languages.
There is no expectation of per-language support for anons, sorry. Log in if you want language support.