Dear @Nima,
Welcome back to the Wefugees Community and thank you for your question.
Unfortunately, I am not an expert on the 19d residence permit - but I tried to make some research.
According to the Refugee Council in Lower Saxony, the residence permit according to section 19d (1a) will be revoked, if the employment contract will be cancelled due to reasons you are personally responsible for. I also read in this brochure that the Agentur für Arbeit needs to check a job offer prior to the issuance of the residence permit. Therefore, I would highly recommend to contact and consult the immigration office (Ausländerbehörde) BEFORE you change your job.
However, I will also link my dear colleague @mbeon-Christine here. Maybe she can add some advice of correct me, if needed.
In any case, please don't hesitate to get back to us with any further questions.
All the best,
Meike