How do I unlock my iPhone 13 mini from carrier restrictions?

Connect your phone to your computer and restore it. If it is truly unlocked you will get a message saying it is.

How to unlock your iPhone for use with a different carrier - Apple Support

Try the advice from Lawrence Finch. I have never had to restore a phone when switching carriers. I would be surprised if the restore works, but hope I am wrong.

Put my Spectrum SIM card in it.......So, the phone was locked to Spectrum

Two years later I’m switching carriers and Spectrum said they unlocked it......They didn't

Yet the SIM card says carrier locked......Because it is still locked to Spectrum. If the SIM was unlocked, you would see a message of No SIM Restrictions

Verizon says Apple is wrong. Spectrum (Verizon) is wrong. If the SIM was unlocked, you would see a message of No SIM Restrictions.

because it still says Carrier locked on the sim. Because Spectrum (Verizon) is lying to you. If the SIM was unlocked, you would see a message of No SIM Restrictions.

Our advice.......unless you decide to stay with Spectrum (Verizon), sell the phone to a Spectrum (Verizon) customer.

For general information, this is almost exclusively a US problem. The EU, and even Canada, have banned selling carrier locked phones for several years. Collateral damage from a capitalist economy.