Why is output falling? Are there other countries taking the market share? Or is there more to it?
1) Ever since the Cold War ended, German companies have been shifting production to cheaper places in Europe, so less and less "German" cars are actually built in Germany and show up as German industrial production.
2) Germany used to sell a lot to China, but Chinese companies are upping their game and shifting to EVs, and Germany is losing Chinese market share as a result.
3) Those same Chinese companies are increasingly selling overseas and starting to kick German butt. I went to an EV car show recently, and while Volkswagen Group had a large presence (VW, Audi, Cupra, etc) and some of their EVs looked pretty good, the prices were consistently 20-50% above the equivalent Chinese models.