In Japan, only international delegations were in a bubble, and officials could leave and enter the Olympic city.
In China, no one is allowed to leave the event location, including staff. And when it is necessary to leave the place, they go in well-identified vehicles, so that in case of an accident, the support teams take the necessary precautions.
That's a good approach. If we want to move things with covid19 then we have to place such restrictions. Even with such restricted approach you cant guarantee there will be zero covid19 case in winter Olympics but good thing is winter Olympics are going to start on scheduled date. I am excited to see ice hockey in action.