I like asking both, but these days a lot of the "what do you do for fun" answers are just consumption hobbies (e.g. I watch X show on Netflix) that people use to switch off after a long day of work. It's easier to think of interesting follow up questions about someone's work than about these kinds of hobbies. Even if (especially if) the work is something completely different from what I'm doing.
As the sister comment said: "Not if they work outside of tech…"
And not even then, in many cases. I know exactly what I do, but having to explain that to anyone, including people in tech, is difficult.
And, you know, it's not interesting to talk about. Talking about that is fine at the job, that's what we do. I have no interest in talking about that when I'm not working. Instead I want to talk about other things. Hobbies, activities, music, books, whatever. Enquring about someone's job will not lead to that at all.
Some people are recently laid off, and asking what they do for work might sting a bit.