As a result the modern ID card system and citizen registration is decentralized by design. When you move between two Bundeslände (states), your records are digitally transferred. They may not under any circumstances exist in two. They get held in a kind of digital holding state during the transfer.
Post-Nazi Germany is one of the most privacy conscious nations I’ve ever seen. Germans still largely insist of the privacy on cold hard cash. Credit card uptake is still vastly lower than neighboring countries. Privacy laws are stringent and well defined. Usage of dashcams and ring cameras are challenging to keep legal.
I trust the German state more with an ID card system than I would the UK for example. British citizens have long given up their rights meekly to be spied on by their government and the UK government has a poor record of safely delivering well designed large IT projects.