"The Support Matrix also shows Cellebrite’s capabilities against Pixel devices running GrapheneOS, with some differences between phones running that operating system and stock Android. Cellebrite does support, for example, Pixel 9 devices BFU. Meanwhile the screenshot indicates Cellebrite cannot unlock Pixel 9 devices running GrapheneOS BFU."

Not surprised at all that an open-source, third party Phone OS is tougher to crack than the Google official version.