You're not wrong but I think the point is to differentiate between the computer science "academic" answer and the engineering "pragmatic" answer. The former is concerned about correctly describing all possible behavior of the compiler, whereas the latter is concerned about what the actual experience is when using the compiler in practice.

You might argue that this is redefining the question in a way that changes the answer, but I'd argue that's also an academic objection; pragmatically, the important thing isn't the exact language but the intent behind the question, and for an engineer being asked this question, it's a lot more likely that the person asking has context for asking that cares about more than just the literal phrasing of "are compilers deterministic?"

> To me that implies the input isn't deterministic, not the compiler itself

or the system upon which the compiler is built (as well as the compiler itself) has made some practical trade offs.

the source file contents are usually deterministic. the order in which they're read and combined and build-time metadata injections often are not (and can be quite difficult to make so).