I believe lockdown mode shows notifications with a specific hand blocking icon when it blocks something. Maybe that was a indicator. Also, we’re talking about the FBI CART here. They have lot’s of experience and based on public contracts, definitely use Magnet Forensics Graykey for initial access into iPhones. Explicitly saying lockdown mode vs unable to extract device are two different things.
My theories:
USB restriction bypass that graykey uses was blocked by lockdown mode
USB could’ve been successful but lockdown mode blocked the graykey agent from being deployed.
FBI assuming things and the new iOS 26 (Wired Accessories) feature is blocking their access.
extra:
FBI consulted with Magnet Forensics support and concluded the phone was in lockdown mode.
This case is very juicy, because if there’s a case where the FBI would want to use all of it’s forensic capabilities, it’s this one, as it includes TS leaks and the president mentioning it.