[Gelöst] Issue with language dropdown button

Background of the issue:
I am trying to fix the language selection button on my website's header. The site is versteckter Link, and the issue is on the page versteckter Link.

Symptoms:
The language selection button in the header is displaying random characters like "™���๨ ��^r�+�'`z" instead of the proper text.

Questions:
What could be the solution for the language selection button displaying random characters?