investgate file system API / OPFS
FF111+: Origin private file system access is now enabled, a new storage API that enables web applications to store and retrieve data from and to the filesystem in a sandbox. - 1811001
dom.fs.enabled
e.g. does it leak timezone, chrome language?
1748667 [meta] Add support for the WHATWG File System Standard
edit: also disk leak, sanitizing, FPI isolation?
Edited by Thorin