Hi. I have bought this phone (16/512) from tradingshenzhen and can tell one thing - after some reboots (approximately 10, I haven't counted) it will stop working. The only thing that you can do to make it work again is to reset user data.
I posted a question on tradingshenzhen that the region lock problem is still there, but they haven't posted it and the rest of conversation with support was continued via email.
As for OnePlus, I can say that they claimed it will be ,,repaired" for free, but for one day I haven't received any details about it.
To summarize,
please stop buying this chinese model, because at the end you will be f*ced up by Tradingshenzhen and their "
No Region Lock Problem" and OnePlus / Oppo ? because it is their new standard how to handle a customer with region lock - it is not a bug, it is definitely a feature

If you don't believe me, then simply try to run adb logcat while starting a device
(modem will not start and the message won't appear too)
Here you have pictures with responses from OnePlus, Tradingshenzhen and region lock:
Access Google Drive with a Google account (for personal use) or Google Workspace account (for business use).
drive.google.com