What is the authenticity of the narration from Ibn Abbas that the Prophet, may Allah bless him and grant him peace, used to pray twenty rak'ahs in Ramadan, and then perform Witr?

The Hadith narrated by Ibn Abbas, stating that the Prophet (peace be upon him) used to pray twenty rak'ahs and Witr in Ramadan, is extremely weak. This is because it is transmitted through Ibrahim bin Uthman Abi Shaybah, whose weakness is agreed upon. Scholars have judged it to be weak or fabricated due to its contradiction of the authentic and established Hadiths from Aisha (may Allah be pleased with her), which state that the Prophet (peace be upon him) "did not increase beyond eleven rak'ahs in Ramadan or at other times."