Basically: Unlike the EU Charter of Fundamental Rights, US 4th Amendment doesn't cover non-US people outside the US, and it only covers government warrents. What Facebook does with your data is not covered by the 4th Amendment. What Facebook does with your data is covered by Article 8 of the EUCFR.
Here's a report from the EU commission about why the US constitutional/legal protection is much less than the EU (and hence German) equivalent:
Basically: Unlike the EU Charter of Fundamental Rights, US 4th Amendment doesn't cover non-US people outside the US, and it only covers government warrents. What Facebook does with your data is not covered by the 4th Amendment. What Facebook does with your data is covered by Article 8 of the EUCFR.