This specific build ID (9599143) corresponds to an update released for Phasmophobia on Steam around . This era of the game was significant as it followed the major "Apocalypse" update, which introduced:
: Enhanced tools for player moderation within the lobby system. Technical Context of the File
between this build and the current version.
: Older builds are often used for private LAN setups that do not require an active connection to Steam’s matchmaking servers.