Yes, things are back to normal now, so no immediate problem.
The main reason I reported it here was that the progress indicator was temporarily broken, and that’s maybe something that could lead people to believe the update has crashed (not sure how much can really be done here).
This was not the case, though. The server is a test server (we need to do quite a bit of prep) and I usually run updates after midnight, so I think I was probably the only user.
So the other question that came to my mind afterwards is: does Discourse effectively require an SSD for communities like ours (~6k users, ~2.5M posts)? Because the current server is decent (AMD Ryzen 5 3600, 64GB RAM), but it does have classical spinning disks and if that’s a problem, we would need to switch to one with SSDs for before we go live.