United States No Longer Risk Area
As of Sunday, June 13, 2021, the United States is no longer categorized as a risk area according to the Robert Koch Institute. Thus, travelers are no longer required to register digitally for entry or quarantine on arrival in Germany.

The requirement to show proof of vaccination to the airline still applies
All air travelers six years and older who are entering the Federal Republic of Germany must be tested prior to departure. The test is waived for fully vaccinated or recovered air travelers. These persons no longer have to present a negative test prior to departure.

source: German embassy website