Apple devices will eventually have randomized serial numbers. Previously, their serial numbers contained details such as the location, date and time the devices were produced. Future Apple devices will contain a randomized 10-12 digit (first it will be 10) serial number that does not provide such details.
The move will hopefully reduce fraud by making it more difficult to generate fake serial numbers. A disadvantage of this decision is that it will be more difficult for device owners to ascertain which batch their devices came from.
The decision was originally announced in early 2020, but was delayed until some time in 2021.