Miami does private defenses & I miss the public component. At UMN, I had a public presentation with friends/family & then a short private exam/vote. I believe your committee had to approve your diss document as ready to defend (essentially saying you would pass) before you could schedule the defense

UMN started doing public portions over Zoom during COVID and still does some now based on student/committee needs, and those are actually really community building as well as alums will log on to support their former lab mates during their defenses