Even if everything was done except optimization and bugs. The build times, doing commits, merges, pulling down builds over VPN can add significant time to projects that are big. Then working over remote with a large team on a project like this would be more difficult especially for the more junior devs or others who aren't used to it. Covid is probably not the major source of the delay, I suspect its a combination and they want to re-work somethings based on feedback. The length of the delay will be more telling and I suspect there may be more delays as we get into the fall season or we could see games even buggier than normal.