You don't understand how much of a problem this is. Since their arrival starting in 2015, these Syrians have obtained German passports, many of them through fast-track procedures. Integration of such a large ethnic group within this short period of time is impossible. Another major problem is that these "German" Syrians are no less criminal than their non-citizen countrymen and no less susceptible to radical Islamic ideology - yet in all crime statistics, where immigrants are already overrepresented anyway, they are now listed as "Germans". This means that attributing their crimes to the immigrant environment becomes statistically impossible.
Finally, this creates a crucial problem for the AfD and its immigration programs: how do you deport de jure German citizens back to their former homeland when they now hold German citizenship? To achieve this will require rewriting the constitution, and how the AfD intends to accomplish this in a democratic country is a question to which the party has so far formulated vague to unsatisfactory answers.