Germany sells a ton of weapons to Israel, and they also buy weapons and surveillance tech from Israel. German foreign policy is basically copy-pasted from Washington, and they are all-in on the US empire (which the German capitalists benefit(ted) from massively, at least up to recently), so every reason the US has to support Israel also applies to Germany.

It also allows them to transfer their guilt/responsibility to Muslims, which are convenient punching bags for politicians to use in order to gather votes from the Islamophobic German public. And it makes (made?) them look good: they can pretend to have learned from the Nazi past, and pretend not be antisemites by getting approval from (Zionist) Jews, which, in the past, actually improved their image domestically and internationally (in the all-important West at least). And, like I said before, it gives them an air of moral superiority and righteousness to pretend they're totally reformed, no longer Nazis, seen the error of their ways (swear to god!). And they can lord that over their enemies, and use it to convince the public to support military aggression in the name of defeating another Hitler, or preventing another Holocaust (which is Germany's special responsibility, you see!).

With what Israel is doing right now, and social media showing the utter horror, it no longer looks very good internationally, but domestically, pro-Israel sentiment among the German public (and even more so institutionally and and in the press) is still incredibly high, so saying the most unhinged pro-Israel shit is actually genuinely popular. And with the repression of pro-Palestinian voices that's not going to change anytime soon either. People are genuinely afraid to speak up, lest they get fired, smeared, blacklisted, or arrested. German language media is like US media from 30 years ago in terms of uncritical pro-Israel views.