> While the protests are per se not illegal, the people arrested aren't accused of just protesting, they are accused of supporting a terrorist organisation. The right to free speech isn't as all-encompassing in Germany as it is in the USA, so shouting the wrong slogans can very well get you in trouble.

Yes, that's correct. Anyone who protests and grabs the attention of the police is accused of supporting a terrorist organisation. That's why I added the information that although they protest completely legally, they still get arrested and deported. The pretense for the arrest and deportation is that protesting to stop the carpet bombing of Gaza supports Hamas, which is designated as a terrorist organisation.

Thousands for weeks on end protested the carpet bombing of Gaza, Germans as well as Foreigners. Many respectable foreign and German organisations invited to participate and organized those protests. And only very few of those protesting were arrested or even investigated.

Those who were usually did something more than protest, like showing support for terrorist organizations like Hamas or ISIS by showing the respective flag, harassing counter-protesters, shouting controversial slogans like "from the river to the sea..." (which is thought to imply destroying Israel and therefore "Volksverhetzung", although I'm not sure if the courts are already through with that one) or just plainly calling for the killing of Jews or the eradication of Israel.

Actually, the police was very patient and tame with those protests, too patient and too tame for the taste of many. A common, not totally unjustified opinion was that if those protests were just Germans protesting about a strictly German issue (like "Stuttgart21" or "Startbahn West" back in the day) and behaving like the pro-Palestine protestors did, there would have been riot police tear-gassing and bludgeoning everyone within half an hour.