[OnePlus 10 Pro] beatbreakee:
i wouldnt advise ANYONE with an original TMOBILE device, ANY attempt to flash ANY firmware from the official builds just yet. Tmobile embedded a VERY WELL HIDDEN check into the EFS partition that only appeared in builds after 11_A.14 ... This check forcefully activates a lock triggered by the CarrierDevicePolicy.xml in the efs system... and if the Region and model does not match the original build that it came with, all of your apps will be completely disabled and there is nothing accessible but the settings button. It also disables ADB/USB debugging completely, and deauthorizes your computer from the adb wireless keys too... then it removes the USB DEBUGGING toggle from settings, followed by a persistent message that your phone is "Violating Contract Policy... Please contact after sales for support" ... Tmobile cannot remove this warning... and even them sending an UNLOCK request to your phone for APPROVED will get ignored by your phone. You can hear ringing, but cannot accept calls... hear emails but not open them,.. and you dialer is in emergency calls only!...

At this point you will think panic is the only option, but instead just Pull your sim card, and use your buttons to force reboot and enter recovery .... Then do a Format Data ,,,, followed by a reboot, but do not put your sim back in... Until you go thru the whole setup wizard, enable usb debugging, and then flash a rollback package to a fw earlier than the one i listed above, your phone will INSTANTLY lock again any time you insert ANY sim card.

Im very sure that there is a system process that can be disabled which will at least block the lockout.... but i dont have that knowledge as to which process(es) are calling it! A logcat generated about 15 screens on my computer as soon as i plugged a sim in... so that was too much for me to sift thru. This is present on both the 10 Pro and 10 T so be warned.... If you are already not using your original T-MO firmware, but you also have been loading other regions with no problem, that does not matter.... I have found an exact reference to the ORIGINAL FW build and Model # that was loaded by TMO at the factory level, in several different TXT and XML files inside the EFS part. AND my 10T and 10 Pro BOTH have been fully bricked, then formatted and flashed thru an authorized MSM Account.... Doing an ERASE ENTIRE FILE SYSTEM, thru msm, did not get rid of this file, so i doubt a twrp level wipe will do it either... MAYBE an "unlock Critical" in Fastboot, followed by a "Fastboot wipe", "DM-verity disable", and "VB-Meta erasure" MIGHT take out this crazy security system, but i know this .... if you flash an original FW using TWRP, it has protections in it to keep IT (twrp) from being overwritten, so you might find yourself in bootloop territory if you region hop.... cuz the fw might notice the changes to the partitions... For now, until someone is brave enough to challenge the Android 12 kernel and remove these trapdoors, I would just be happy you have TWRP, and wait for the person who finds and slays the Tmobile Dragon hidden in our phones! But this is truly an android 12 function that was put in place for Carrier and Manufacturer benefit ONLY. Another strike against 1+