Putin ... He is not looking to attack Germany or other Western NATO countries. Why are Germans talking of war?
They do believe that Russia wants to geographically expand, to get more countries under it´s control, with especially the small Northern European ones (Estonia, Latvia, Lithuania) possibly "the next ones".

do they really believe it?
Why do you think Finland 2023 finally after all those years joined NATO? And in 2024 Sweden?

US and Europe upset the apple cart by expanding NATO
Correct. Since decades NATO constantly expands eastwards (the German expression for it: "NATO Osterweiterung"). Russia again and again warned that´s unacceptable. 2021, before(!) the invasion of Ukraine, they again warned about "red lines" they can´t allow the West to cross, mentioning specifically the planned admission of Ukraine into NATO (2008 NATO promised to allow Ukraine to join NATO).

But: Nobody here in Germany sees that this is the cause for what´s happening, that this is self-inflicted. I wonder what Americans would do if Russia moves heavy weaponry weapons to their front door (Actually we know: Cuba crisis). The really disturbing thing is that nobody here talks about that, as it would disturb the black-and-white picture. Bias in action: It can´t be true what otherwise would cause cognitive dissonance: That you yourself are causing the bad that´s happening to you. There must be an external cause.

This is why I am scared. Because politicians and media are so switched into line, with the few critical voices pushed into a corner and labeled "Putin-Versteher" (Literal: "Putin Understander", but meant dismissive, not in the usual positive way "understanding" is meant). It is a circle, and with the word "Diplomacy" not even allowed ("Are you one of those 'Putin Versteher'?") I don´t see a way out.