@Redav
A bit of background; because for once, migration isn't the actual problem here.
German language proficiency for state employment is proven through a series of tests (dictation, essays, verbal tests) which are now beyond the capacity of most Gen Z recruits, including the majority of autochthonous Germans.
That's because they reflect an education system that doesn't exist any longer.
Each German state has its own education system, and they were all run into the ground collectively over the past 25 years.
The conservatives screwed theirs by streamlining the curriculum to what they believed facilitated a quick entry into the labour market; the progressives ruined theirs with "alternative education" pipe dreams.
The state of Bremen, a leftist mecca, for example, doesn't even require grammar proficiency in elementary schools any longer. The pupils there are to learn to write "by ear", I kid you not.
As a result, proper handwriting is no longer taught, and most pupils have a drastically reduced vocabulary and limited understanding of written German, which differs from spoken German quite wildly. For example, in spoken German we only use present tense and perfect nowadays; in written German, imperfect and pluperfect are used instead.
Last but not least, German government agencies use a particular jargon often called Chancellery German, which employs a great many words the average person has never even heard.
Hence the mentoring.