@evan the Palestine flag was never, to my knowledge, illegal in Germany. You're thinking of German Criminal Code (Strafgesetzbuch ) Section 86a, deemed to ban symbols of what the Federal Constitutional Court declares terrorist organizations. Thus, the flags of Hamas, PFLP, and Hezbollah are so classified, but not the Palestine one.
(Disclaimer: Not an expert, and I've relied on secondary sources in English, not primary ones auf Deutsch.)