iPhone 15 Pro Bluetooth connection issues after upgrading from iPhone 12 to iPhone 15 Pro

“Upgraded” from my Iphone 12 to a 15 pro and can’t connect to most of the Bluetooth devices that the 12 connected to.

The 12 is still operating so I can easily do a side by side comparison with the 2 phones.

I’ve read the blogs, followed the unpair, repair, factory reset, etc instructions with zero success.

very frustrating.

Would love to hear from someone who can verify that replacing the phone fixed the issue.

[Re-Titled by Moderator]