I posted about it above, he’s on record during an interview saying his nickname was due to his anger issues as a kid but here’s a source:
https://usatoday30.usatoday.com/life/people/2005-08-16-p-diddy_x.htm
Puffy
“Whenever I got mad as a kid, I used to always huff and puff,” Combs told Jet magazine in 1998 to explain his original nickname. “I had a temper. That’s why my friend started calling me Puffy.”
