[Cerrado] language switcher menu pointing to wrong URL

Background of the issue:
I am trying to set up the language switcher for my website, which has two languages: Italian (IT) and English (EN). The issue can be seen on this page: enlace oculto.

Symptoms:
The language switcher in the footer is pointing to incorrect URLs. When I select English, it redirects to: enlace oculto. When I select Italian, it redirects to: enlace oculto.

Questions:
Why is the language switcher pointing to incorrect URLs?
How can I fix the URL redirection issue for the language switcher?