So I thought I would post this here since searching for the error on google did not get any results.
You get this error when you open a page that allows barcode scanning
"visionkit.datascannerviewcontroller.scanningunavailable error 0"
This error is basically telling you that the current app version is not compatible with the device. There is a KBA on what devices are not compatible with v18.3 or higher.
https://support.servicenow.com/kb?id=kb_article_view&sysparm_article=KB1702599
