Technically by the rules of grammar it is not. But pointing that out add nothing of practical value to discussion. It is a question in colloquial speech.
For instance:
Person A: "Why did you start livestreaming as a rust developer?
Person B: "Why I started livestreaming as a Rust?"
There, person B is confirming what it is they are supposed to answer.
For instance:
Person A: "Why did you start livestreaming as a rust developer?
Person B: "Why I started livestreaming as a Rust?"
There, person B is confirming what it is they are supposed to answer.