Can't connect iPhone Mirroring to MacBook

I recently upgraded my iPhone and kept my old one, which is connected to my Apple account, and therefore the iPhone Mirroring app on my MacBook running MacOS Tahoe. Whenever I try to mirror my new phone, regardless of whether I am near my old phone, it always tries to connect to my old phone. I have tried restarting both my MacBook and my new iPhone, powering off my old iPhone, and nothing is working. What should I try?