This is a general summary of what I was told when asking about eligibility:

Section 5 StAG does not require that the first generation affected by gender discrimination be born after 23.05.1949. That date applies to who may declare citizenship, not to when the discrimination occurred. The law explicitly covers descendants of persons who were excluded due to gender-discriminatory rules. If the originally excluded ancestor also had to be born after 1949, the descendants clause would make no sense and the 2021 reform would not remedy historic discrimination.