If you were calling the possibility that the US might consider some kind of trade retaliation against Germany for siding against liberal values "zero sum," I would say the struggles between liberal and illiberal values, as well as export-oriented vs neutral economics, are by definition zero sum. On the former, according to Xi Jinping Thought, the US and China are locked in an existential struggle between authoritarian, personality cult state-capitalism and universal liberal values, democracy and human rights.

Xi Jinping Thought on this topic is by definition zero sum (he sees the US as his existential enemy), and since this zero sum conflict didn't start (by definition) until Xi took power, I think if we want to get philosophical, the question would be, why does Xi think in such a zero sum way, forcing a reckoning and change of policy from the West?

Xi's motives are of course difficult to discern, but I think it's a topic worth pursuing and I'm happy to hear your thoughts on it--I still think John Garnaut's framework is the best, Xi and the other red princelings think in terms of power, dynastic power, and are obsessed with breaking the dynastic cycle and maintaining their own power at all costs. Of course, the unanswered question there is, why did they assume only a hardening of the authoritarian system at home, and making hatred of "the other" (the US/West) the organizing theme of daily propaganda life at home for all Chinese, were the best path to breaking the cycle, rather than liberalizing the regime, as many other top leaders (Deng and Zhao Ziyang, for instance) did/wanted to do?

The cynical answer is, they wanted to secure their own power more than anything else, whereas the more lenient answer I would say is, they didn't think the system would survive without much tougher leadership from the top.

On the economic front, the German-US relationship actually is only indirectly related to China, and much more related to low German wages causing a massive trade surplus with the US. Since not every country can suppress wages/domestic demand as Germany (and China) have done, the German/China economic policies are by definition zero sum (since it's impossible to have a world economy with no buyers, if everyone drove wages down to zero we wouldn't have a world economy, so it only works of one party does it and the other doesn't, which is one definition of zero sum).