I agree that it would be
more clear if the visibility-change dialog included some stats about the repo so you can confirm at a glance that it's the right one, but...
it asks you to type the full name of the repo before it will allow you to proceed.
If you do a copy-paste of what it tells you to type, that's on you. The entire point of that box is to get you to think about what you are doing, and explicitly type out the name of the thing you want to change.
Perhaps I've interacted with GitHub's UX enough to be familiar, but when OP put up a side-by-side screenshot and asked, "A 54k-star question: Which one of these two dialogs is safe to confirm and which one deletes a 10-year-old community?" ... I looked at the two boxes, saw the repo it was asking to modify in both cases, and immediately knew the correct answer!
I get that the ideal is that every person who takes any kind of action knows what they are doing and never makes a mistake. I don't know if it's realistic to expect that outcome, but certainly that's the ideal. But how far should UX designers bend over backwards to cater to people who perform destructive actions without paying attention to what they're doing?