Cost cutting in favour of trying to profit with their AI product. It's just that one feature despite security improving a lot elsewhere. They added a weird Gemini colored LED to the back of the new phones. They moved to a new generation processor and they never used MTE in production in the previous phones for almost all of the OS for the devices they had it, being limited to Android's Advanced Protection feature. It's likely they stopped caring about it. Apple has it in some places on their latest iPhones and is always on for iOS.