Ask HN: How did Call of Duty fix "update requires restart"?

Call of duty for years has performed automatic updates when launching the game that required the user to restart the game once applied. This was a very frequent annoyance for many players. Supposedly this is fixed in the newest title launching soon, and I'm very curious what the architecture was that lead to this UX persisting for so long. I would love to hear any first hand accounts, please do not speculate, I can speculate myself.