I would not bring up Covid questions here because the interviews go by fast and this is your opportunity to show why you would be a great addition to their program. You can direct those types of questions via a phone call or email to the school's office, or, in follow-up communications after being admitted. It is inevitable that they will have to share that with you before attending anyway. Let your interview be exclusively about your work and your ambitions as an artist. I've only had one interview so far, and 20 minutes went by incredibly fast. If you have an opportunity to ask a question at the end, I would find a way to make it unique to the committee interviewing you. It's a chance to get their perspective / learn if that fits with what you want out of your graduate education.