https://www.techradar.com/news/getting-off-steam-fallout-76-wont-be-sold-on-valves-online-store

When it comes to the PC version, Fallout 76 won’t be available to buy on Steam, with Bethesda deciding to directly sell the game itself instead.

That’s according to the FAQ for the beta test of the game, which states that the PC incarnation will be available “via Bethesda.net only”. PC Gamer also got official confirmation from Bethesda in a statement which read: “The PC version of Fallout 76, for both the B.E.T.A. and the launch, will be available only via Bethesda.net, not on Steam.”