On iOS 16, Apple added a new level of security around development apps installed from xcode or third-party websites: Developer Mode.
To be able to run an app from xcode on a device or to run a development app, those with an Ad Hoc profile, a device now has to enable a new option: the Developer Mode.
This option is available in the Settings app: in the "Privacy and security" pane, at the bottom of the list: enable the switch, restart the device as required by the prompt, activate as required by the new prompt, and apps can now run.
This applies only to apps with Ad Hoc profiles, and does not apply to those with an In House profile (from an Apple Enterprise account).