According to a recent report by iFixit, Apple is allegedly locking iPhone batteries to bock third party battery repairs.
iFixit have revealed that if a battery is replaced on one of the newer iPhones then a service message is display in the battery settings section on the handset, this can be seen in the picture below.
This apparently happens if you replace the battery on an iPhone XS, iPhone XS Max or an iPhone XR, have a look at the video below.
Put simply, Apple is locking batteries to their iPhones at the factory, so whenever you replace the battery yourself—even if you’re using a genuine Apple battery from another iPhone—it will still give you the “Service” message. The only way around this is—you guessed it—paying Apple money to replace your iPhone battery for you. Presumably, their internal diagnostic software can flip the magic bit that resets this “Service” indicator. But Apple refuses to make this software available to anyone but themselves and Apple Authorized Service Providers.
According to iFixit if the battery is replaced by a non Apple technicain even when genuine Apple battery is used then this service message is display, as yet there is no official comment from Apple on this.