Apple is admitting in an internal memo seen by MacRumors that there is a problem with the iPhone 14 series that results in a pop-up message that says, “SIM Not Supported” which is often followed by the freezing of the device. While Apple said that it is investigating the issue, it did rule out the possibility that it is a hardware problem. The company is asking its customers to make sure that they keep their software up to date.
Bug forces pop-up that says “SIM Not Supported” on iPhone 14 series models
You can always check to see if there is a system update for your iPhone by going to Settings > General > Software Update.