1280
What do you think of this prediction?
(programming.dev)
Steam is a video game digital distribution service by Valve.
Steam News | Steam Beta Client news
Useful tools:
SteamDB
SteamCharts
Issue tracker for Linux version of Steam
So it's Steam > Interface > startup location to open in library, and then uncheck "notify me about additions, changes, new releases," etc. to kill the popup.
THANK YOU!