This is a *bonus* SBB99 weekly event, and it's going down on Saturday July 2nd from 5-8pm PT.
During this time, Storybook Brawl transforms into SBB99, and you'll battle 99 other players (instead of the normal 7).
Want more details? Check out this article by Matt Nass to learn more:
https://news.storybookbrawl.com/articles/2022-06_sbb99_announcement/
Saturday Night SBB99!
Update notes via Steam Community
View more data in app history for build 9032306
Storybook Brawl Content
Depot 1367021
Changed depots in alpha branch