7. Is there a ban on anonymous donations to political parties?

(2) The parties are not authorized to accept donations:[…]
6) Donations, insofar as they amount to more than 500 euros in individual cases and whose donors cannot be determined, or which are recognizable as the forwarding of a donation from an unnamed third party; […]
Source: § 25(2), Political Parties Act, 1967 (amended 2018)

Anonymous donations over EUR 500 are prohibited.