The Ayyubid Dynasty: Conflicts after Salaahud-Deen’s death:

Salaahud-Deen succeeded in saving Egypt and its people from the disadvantages of Shi‘ite rule of the ‘Ubaydi Dynasty, under which Egypt had suffered since the advent of the ‘Ubaydis. Egypt lived one of its golden ages of strength under the leadership of Salaahud-Deen, however, after his death, the Ayyubid state was divided among his sons, brothers, cousins, and governors. His oldest son, Al-Malik Al-Afdhal Noorud-Deen ‘Ali, ruled Damascus, the coast, Jerusalem, Baalbek and Sallkhad and Bosra, Baniyas and Margaliot [Hunin] and Tebnine to Ad-Daroom [Dayr Al-Balah] near the Egyptian borders. His second son, Al-Malik Al-‘Azeez ‘Emaadud-Deen ‘Uthmaan, was in Egypt at the time of his father’s death; so he ruled it. The third son, Al-Malik Ath-Thaahir Ghiyaathud-Deen Ghaazi ruled Halab [Aleppo] and its suburbs.

The brothers of Salaahud-Deen, Al-Malik Al-‘Azeez Sayful-Islam Tughtageen ibn Ayoob ruled Yemen, Al-Malik Al-‘Aadil Sayfud-Deen Abu Bakr ruled Karak, Shoubak and the eastern countries (the Arabian Peninsula and Diyarbakir).

This division ignited the flames of hostility and conflict among the siblings. Consequently, the power of the Ayyubid state waned and this ultimately led to its fall.
We notice that the history of the Ayyubid Dynasty after the death of Salaahud-Deen and until its fall at the hands of the Mamluks was nothing but a series of conflict and wars between the Ayyubid princes. Each of them was trying to seize new land at the expense of his brother or his cousins.

https://en.islamstory.com/index.php/en/artical/20622/Ayyubid-Dynasty