I happen to work for a predominantly German company and hence have a lot of German colleagues - spend quite a lot of time in Germany, fluent in the language, follow the news ... you name it!
To some extent, the "guilt" argument is certainly accurate. Specifically the notion that some Germans see in Israel some sort of a beacon of atonement for past sins, so to speak.
When this is the case, in my experience, this is often genuine and deep-felt - especially (but not only) among the left. There are certainly aspects that, as a non-German, I find weird and frankly problematic - such as what I am tempted to call a level of "fetishisation" of Jewish people that has very little to do with actual Jews. (By the way, this is something that also happens among certain segments of Palestine supporters - I have always hated it). But that is what it is, and I can somehow respect this as a genuine - albeit deeply misguided, in my opinion - attempt to "do better".
However, there is also very clearly a much, much darker element to German "Israel right or wrong" attitudes, and that is essentially when it becomes - and it is doing this - a stand-in and nothing much more than "German nationalism by proxy":
It ought to have us all worried, I should like to think, that, in Germany, being "against antisemitism" and "standing with Israel" is, among other things, a rallying cry for the far-right AfD. And that "imported anti-semitism" is the #1 dog whistle against migrants. That, apparently, pro-Palestinian Jews are more of a problem than one Hubert Aiwanger, deputy PM of the state of Bavaria, a one time bona fide neonazi whose former teachers felt compelled to speak up about him holding office. But he stands with Israel, so that's alright then!
And, most of all: the claim that Israel's existence and security are German "Staatsräson" (about: "state's raison d'être") - once made, among others, by former chancellor Merkel even.
Germans do not, due to their history, really get away with loudly shouting "Germany, gung-ho!" (or "Deutschland über alles", as it used to be). Like in many other European countries, however, far-right attitudes are on the rise in Germany. As is a nasty form of nationalism - it's just that, in Germany, a lot of its public expression is projected upon Israel. Pro-Israeli nationalism is, essentially, the acceptable form of expressing nationalism in Germany.
This is not a good thing - not even if you are pro-Israel!