How old is Po really?
In Kung Fu Panda 2, Shifu mentioned Po found inner peace at such a young age, but Shen waited 30 years to rule over Gongmen City alongside his cannon which he envisioned probably ever since then he started to use fireworks as an weapon not years before he attacked the panda village where Po lived when he was an infant and it's not even mentioned or shown that Shen began to use fireworks as a weapon years before or it was 20 years ago he attacked the panda village and was exiled.
In Kung Fu Panda 3, Mr. Ping mentioned that he raised Po for 20 years before Mr. Ping told him he was adopted and behind the scenes it is mentioned that he is in his 20s.
In Secrets of the Scroll, Po was a teenager 10 years ago.
In Kung Fu Panda: Legends of Awesomeness, episode "The First Five" Shifu mentioned that Po is the youngest member of the Furous Five.