This classification was made by the BfV[0], created in the 50s. They're tasked with finding extreme groups (right and left) that might present a threat to Germany's democracy.
Now, if this should happen and all that, I don't know, but it doesn't seem to be a new thing in Germany (or in other countries like the US where the FBI classifies groups too). In any case and independently of my political views, I can see why a country with Germany's past flags anything that leaves the centre of the political spectrum. I also can see why they're paying attention to this party... their positions about Russia, funding, etc, should raise some red flags.
