iOS 18.1 was released on October 28, 2024. This has nothing to do with recent news coverage where cops are blaming imaginary features for devices not staying in After First Unlock state. Devices likely crashed due to one of many bugs which exist, including already patched ones.
The fantastical theories about iPhones communicating with each other about being kept without cellular access and rebooting based on what they were told by other phones do not check out. It doesn't make sense. Law enforcement has the capability to host properly signed cellular.