Germany has slowed down because the productivity gains from 20 years ago ("Agenda 2010") have run out of steam (Merkel didn't do anything for productivity for 16 years), more recently consumer demand has decreased because Germany was hit by high gas costs (everyone heats with gas) and the current government increased costs for consumers (e.G. everyone needs to replace their gas heating - driven by the minister for the economy, madness! - who is a vice chancellor and therefor minister for economy but needs to play to his green base and does environment policty instead of economics) - so consumers have a very negative view of the future and are very cautious with their money.

Dropping German consumer demand has nothing to do with competitiveness and trade surpluses.