Language switcher fails when baseURL has subfolder/project

[vinser]

When baseURL has a project (folder) and is something like baseurl = "https://blist.vercel.app/project/" menu language switcher routes to wrong urls.
Default English home page url in such a case is http://localhost:1313/project/en/ and for Deutsch it should be http://localhost:1313/project/de/. But when I choose in from Language menu I get http://localhost:1313/de/ instead.
If you enter it manually in browser line all goes well until you try to switch language.

Is there any workaround for that? What I have missed?