Can I disable 'Request Specific Languages' mechanism?

how can I disable the request specific language mechanism? My frontend sends Accept-Language: en-GB,en;q=0.5 because the language setting of the browser is English.
But I don’t want have results in my response in English in my German frontend.

Thanks! Reini

What endpoints do you access?

only my own created in rest-services.xml. My solution was to fix it in the frontend. So my frontend defines in the http header which language is needed.