Huawei stopped bootloader unlocking program as early as in May 2018, would you call it preemptive measure intended to forestall already overhanging American sanctions? I think not. I vividly remember how great thousands of XDA voices suddenly cried out in terror and disgust at the way their prominent sponsor had betrayed them.

Despite obvious connection you’ve pointed to, I still recall how OnePlus leaked EngineerMode app, equivalent to potent rootkit, during routine testing. The Hanlon’s razor might still apply here as well.