Abiy Ahmed (2019), from Ethiopia, ended the cold war with Eritrea. Then he launched a war against the region of Tigray, with mass rapes and mass civilian killings. He harassed the free press, and turned the country into an autocracy.
Juan Manuel Santos (2016) from Colombia and Ellen Johnson Sirleaf (2011) from Liberia later appeared in Paradise Papers because they had secret offshore companies in Panama and Barbades. Their political activity was more tame after the prize than before. Both ended their presidential tenures with plummeting approval rates, especially because of corruption allegations.
Barack Obama (2009) received the Prize for his generous discourses on foreign policy, just after being elected. Then he lead the USA to more war in Afghanistan, and a new war in Libya. He helped Saudi Arabia invade Yemen (UN states this war killed 300,000 people). He helped the Egyptian army with its coup, that killed thousands of opponents and sent 60,000 in jails (including the elected president who died there).
In my opinion, this prize is, most of the time, a dark and heavily political joke.
Aung San Suu Kyi, 1991 prize winner, resided over the genocide of the Rohingya people.