The USA is well aware of what Erdogan is up to.
Now they have a base in Turkey with nuclear weapons - waiting for one of the Erdogen "terrorist groups" to take these UAS weapns just like ISIS did in Iraq.
The USA is also well aware of what Iran is up to.
The USA is also well aware of the ethnic minority groups (Yarzidis, Copts, etc) that are being ethnically cleansed and genocided by the Islamic Facists.
The USA chooses to do nothing - therefore Russia must fill this vacume

Assad government and Kurds want to ethnically cleansed Turkmens of Syria, I suppose defending yourself is a crime as it was in the 1940s. There is no evidence that Turkey supports ISIS, just because Assad and Putin say they do does not make it a fact.

it is unlikely that germany only now realised that erdogan supports terrorists.
it is the failed coup and the subsequent imprisonment of tens of thousands of turks, many of them innocent, that has prompted germany to make this public declaration.