Urgent Account Concern — Verification Lockout & Security Risk Tied to Old Device, what needs to be done in order to remove old device from account?

Recently, during a visit to a T-Mobile store, I was advised—quite emphatically—to disable the “Find My” feature on my iPhone. The representative’s insistence on this particular action stood out, as no other troubleshooting or transfer steps were emphasized. At the time, I complied, but I was not provided with any further explanation or guidance regarding the implications.

Since then, I’ve encountered a series of escalating issues:

• My old device is still linked to my Apple ID and appears to retain verification authority, meaning it continues to receive two-factor authentication codes and account recovery prompts.
• This is now preventing me from fully accessing or authenticating my new device, effectively locking me out of several key apps, services, and systems.
• I am concerned about the potential misuse, unauthorized access, or vulnerability of the old device, particularly since I no longer have possession of it and cannot confirm its status or handling.

Given this sequence of events and the emphasis placed on disabling “Find My” (a core security feature tied to Apple’s Activation Lock system), I find the situation troubling and would like to better understand the potential motivations or risks involved.

Key Concerns:

1. Security Risk – The old device, now unprotected and still authorized for verification, could pose a serious security threat if compromised or misused.
2. Account Lockout – I am unable to access critical services or accounts on my new device due to residual verification control from the old one.
3. Procedural Red Flags – The T-Mobile representative’s insistence on disabling “Find My” —without full device unpairing, iCloud removal, or deauthorization—raises questions about whether standard protocol was followed or if something irregular may have occurred.

Request for Support or Insight:

• What are the technical and procedural implications of disabling “Find My” without fully removing a device from an Apple ID?
• Could this action have enabled unauthorized access, resale, or modification of the old device?
• What are the recommended next steps for recovering full control of my Apple ID and verifying device integrity?
• If this situation could involve mishandling, what internal escalation channels exist within T-Mobile or Apple to report and resolve it?