“Steam Cloud is stored under userdata[account id] if you wanna check

It will also create encrypted copy of configlocalconfig.vdf.
This file contains your steam friends, their name history (groups you’re part of, are considered “friends”).

It seems friends might be used for friends suggestions, but I don’t even use that feature and it collects more than that.

While it’s called “localhistory” it is synced from cloud

It will read, encrypt and then write copy to: C:ProgramDataEpicSocialBackupRANDOM HEX CODE_STEAM ACCOUNT ID.bak
It will also keep historical entries there.”