According to a report from MacRumors, they have gotten their hands on an internal memo sent to Apple Store employees which basically instructs them not to provide repair services for iPhones that have been marked as lost or stolen in the GSMA Device Registry.
For those who might be unfamiliar, the GSMA Device Registry is basically an international database of sorts where smartphone owners can report and register instances where their phones might have been lost or stolen. Since these reports rely on a device’s IMEI which is unique to each handset, it allows companies like Apple to check for these types of reports when a phone is brought in for repair.
Apple had previously rejected iPhones that were lost or stolen but only if it had the Find My feature enabled, so by expanding their coverage to the GSMA Device Registry, it allows them to also include devices that might not have the Find My feature enabled.