From 27.02.2022 Bulgaria is excluded from the list of highly risky countries, which is why the arrangers are not required pre-digital registration at https://einreiseanmeldung.de and mandatory entry in quarantine after arrival in Germany for unvaccinated, unprecedented and children below 6 years of age.
The general obligation to present a negative test, a vaccination certificate or medical certificate for all persons who have reached the age of 6, irrespective of the type of transport to Germany arriving in Germany, continues to be applied. The obligation is also in force for passengers carrying out the transfer of German airports.
All available information with requirements can be found at: