It was because a method was discovered to bypass the lockout of stolen devices.

As an early OnePlus user (1, 3, 5, 7, 13) i find myself unimpressed with what Nothing is proposing, feels more like a design exercise than a flagship killer

They consistently have allowed bootloader unlocking without extra fuss and have had good LineageOS support. That is their main appeal, IMO. Nothing phones had no LineageOS support until recently (spacewar is now supported, unsure about other models), and it's not clear if there's enough of a community/following to keep putting LineageOS on them. I do not want any phone where I'm stuck with the stock ROM.

Yup - and worse than that too.

In the last week or two it's been rumoured that Oppo are pulling the plug on OnePlus, and are going to wind up the brand entirely. (Although it may cling on in certain markets, like India).

I've been with OnePlus since the beginning, and am not at all impressed by the Nothing. Primary missing feature which I've come to depend on, off screen gestures, is missing. And the device just comes across as foreign in general; makes me think of the iPhone, which is not something I want to think of.

He has already made the video on this, but it is only 3:23: https://youtu.be/3AiRB5mvEsk?si=XapAHhHRJtssDI4F

Lots of CPUs that have secure enclaves have a section of memory that can be written to only once. It's generally used for cryptographic keys, serials, etcetera. It's also frequently used like this.

Fuses are there on all phones since 25+ years ago, on the real phone CPU side. With trusted boot and shit. Otherwise you could change IMEI left and right and it's a big no-no. What you interact with runs on the secondary CPU -- the fancy user interface with shiny buttons, but that firmware only starts if the main one lets it.

This is in the Qualcomm SOC chip, so it's not something that has to be designed into the phone per se.