Come on, he says exactly "This is my Persona" in Japanese. Not every line needs to pop with "flavor", and adding "flavor" where it wasn't initially is just less accurate. You can call it google translate-tier if you like, but it does a far better job at conveying the same message as the original line than "wassup persona" does, not to mention it sounds far less forced and unnatural than "wassup".
The new line sounds straight up bad, is nothing like the original line and it's not a change for the sake of paraphrasing to fit the lines in sync with the animation, since his original line would fit perfectly. It's just a change for the sake of a change, and it just adds cringe that didn't need to be there and is bound to take plenty of people out of the moment. It's poor translation and the "google translate" tier line is far more accurate, more befitting of his character, and more faithful to the original script.