What is serialization and how does it affect you?

Serialization occurs predominantly in phones manufactured from the year of 2018 onwards. It is the process in which the manufacturing company links certain parts of the phone to communicate with each other through means of chips (or ICs). 
In certain cases, these can simply yield an error on your screen (such as the iPhone screen and battery replacement errors) which does not affect the overall functionality of the device. You can still replace any damaged parts at an affordable price on such devices, however their resale value might decrease due to the original part having been replaced.
In other cases, serialization can yield in certain parts of the phone becoming non-functional; regardless whether said part was replaced or not. A great example of this is present with the Samsung A line of phones (A50,A70 etc.). The screen on these phones can be quite expensive to replace to begin with due to their AMOLED technology. However, a replaced screen can yield in your fingerprint sensor not working due to the fact that the replacement screen needs to have the original IC transferred over.  Realistically, this process is very risky to be done via conventional means, and usually involves having CNC machines which can be very expensive in order to avoid these sort of issues.
In newer cases, with the likes of the iPhone 12 series and more recently reported Huawei P40 line-up, any hardware change can yield the device partially working or becoming totally inoperable.  The Huawei P40 line-up for example, fails to boot if the battery, a consumable part which degrades over time, is replaced.
Serialization is an on-going issue and there is a big battle between the repair industry and the manufacturing giants such as Samsung, Apple and Huawei for the RIGHT TO REPAIR devices of all kinds. What you can do as a customer / concerned consumer is inform yourself of all matters surrounding the right to repair and sign any petition which supports the right to repair movement. At the rate that this issue is continuing, the repair industry can and eventually will become a thing of the past due to the tools required to be able to service these devices.