To apply for naturalization by descent under art. 116 Basic Law and § 15 Law on Citizenship, your ancestors must have lost their citizenship based on racist, political or religious grounds.
Decisions under the Act on the Revocation of Naturalization and the Withdrawal of German Citizenship of 14 July 1933 are always assumed to be based on political, racial or religious grounds. Mainly, Jews who fled abroad were expatriated under this act. The same applies to the revocation of citizenship in accordance with the Eleventh Ordinance to the Reich Citizenship Act of November 25, 1941.
Other cases of expatriation may also have had racial, political, or religious reasons, but this must be proven in each individual case. The definition of political reasons is quite broad, and various cases may be considered. Examples of this could be expatriation due to homosexuality or desertion.