Steam limits game auto-updates to manage peak demand:
Console makers aren't the only ones managing game service bandwidth to keep traffic flowing during the COVID-19 outbreak. Valve is scaling back game auto-updates in Steam to "spread out" the load and prevent its servers from buckling under the strain. As of this week, only games you've played in the past three days will get immediate updates. Everything else will be updated over the course of "several more days." You can still manually start updates and schedule update windows, of course, but Steam won't be in a rush to keep all your games current.
(Score: 3, Interesting) by EvilSS on Tuesday March 31 2020, @10:19PM