I haven’t read any such study myself, but it sounds like a BS study. Anything that controls a person’s life can be considered an addiction. There are certainly people where porn has controlled their lives. One person who’s been very vocal and brutally candid about how it was ruining his life is The Primeagen, a coder on YT. My best friend’s father died in huge debts because he was buying copious amounts of porn outside of his means, and phone sex lines. That’s addiction.