As Sean “Diddy” Combs celebrated his 55th birthday in the stark environment of the MDC Brooklyn detention center, the contrast between his past lavish festivities and his current circumstances couldn’t be starker.

The once glitzy life of the music mogul now shadows the gray walls of a prison cell as he faces severe allegations. Sean “Diddy” Combs’ birthday unfolded far from the public eye this year, marked not by champagne and red carpets but by…