Last days many Reddit users confirmed that iOS 11.3 is blocking the work of not original displays on iPhone 8, 8 Plus and X, installed by non authorized service centers.
However, even in the authorized Apple service centers, there is a risk that one of the function of your iPhone may stop working. It's about the light sensor. That means that after changing the LCD display, your iPhone stop detecting if its dark in the place you are or if you are under the light of the sun.
Some of our partner services for FirstHelpTech as well confirmed that even though they mounted original displays, after a while, the clients come and asks to fix the light sensor.
The explanation is that while assembling the Apple smartphone is used a special machine called Horizon. The machine tells to the phone that the actual assembly is made by original Apple parts. A change of any iPhone part without Horizon machine are likely end up that the part won't work.
Last year, Apple spread around 400 machines for the 4,800+ authorized repair centers from 25 countries. And of course there are many countries and places where iPhone users can't repair their phone
It's sad that Apple decides where users will fix their phone, but on the other side is not insure the necessary machines at least in the authorized service centers.
A solution still exists. You can send your phone to apple repair centers. The procedure and information you can find on Apple Support. There you find also the price for such repair that varies from 29 $ with AppleCare+ to 279 $ out of the warranty.
Thus, take care of your iPhone and try to use silicone cases to prevent any accidents.