Pope-Dippel had left the AfD, said party and faction leader Robert Lambrou on Sunday at the German Press Agency in Wiesbaden and confirmed media reports.
The Hessian AfD parliamentary group now consists of only 14 MPs.
According to a report by the "Hessisch/Niedersächsische Allgemeine", Papst-Dippel gave differences in the corona debate and in the preparation of electoral lists as reasons for her decision.
At the end of last year, the two deputies Walter Wissensbach and Rainer Rahn had already declared their withdrawal from the party in a dispute over the political course in the AfD.
In mid-2021, MP Rolf Kahnt left the AfD.
He regrets Pope-Dippel's step, said party and faction leader Lambrou.
There was no sign of the decision.
However, Papst-Dippel had failed in drawing up the list for the state elections when applying for a promising place on the list.
The AfD entered the Hessian state parliament for the first time after the last state election in 2018.
With a result of 13.1 percent, the party won 19 seats.
However, because the elected MP Alexandra Walter was suspected of having spread right-wing extremist ideas, she was not accepted into the Hessian AfD parliamentary group.