Good character writing is key to making expository conversations less blatantly expository. What are their motivations? What's at stake for each party? What are their worldviews and personalities? Once you have that figured out, you allow it to flavor what each side says, how they say it, and where it fits into the overall conversation. It will feel less like the author using a character as a mouthpiece and more like something that would actually happen.
You should aim to have some back-and-forth. Don't let one character drive the conversation, with the other mostly along for the ride; the interviewee should exercise agency in deciding what information to relate, and the interviewer should (at least) nudge them towards giving whatever information the interviewer wants. One-sidedness really drives home how infodumpy the interview is, so avoid it as much as you can afford to.
Break it up a bit. Intersperse it with parts that aren't expository — be it characterization fluff, plot-relevant events, or even some other activity that the interviewer and interviewee are participating in. This serves to keep it feeling connected to the article/setting as a whole (infodumps are annoying in part because they take you out of the moment) and just gives the reader a bit of a breather.
This may seem obvious, but if you're really worried about having too much exposition in the interview, try to shift it around to somewhere else or just skim over the boring parts of the backstory.