Welcome to the Wefugees Community and thank you for reaching out to us.
Based on the very few information provided, it is difficult to give a profound and clear answer. In general, according to the Dublin-III regulation, the country which issued the Visa will be responsible for the asylum application. If you apply for asylum in Germany, there is a chance that the authorities will send you back to Bulgaria. But this needs to be assessed individually. Please see also the following thread, in which a similar question was discussed: Can I apply for asylum in France if I have a valid visit short stay visa issued by the Swiss Embassy?
Do not hesitate to get back to us if any clarification is needed or if you have further questions.
All the best,