iPhone LCD Model
On iPhone 7 Plus and 8 Plus devices, when using OEM screens, make sure to pair the device's original screen to the one being installed. If you install a different Manufacture's OEM LCD on to an iPhone that is calibrated with another manufacture, you are bound to have touch issues either immediately, are shortly down the road. Using a EEPROM reader and copying screen data from one screen to another does not solve touch issues. EEPROM reader only helps with true tone compatibility.
". If you install an LG 3D touch panel into a Toshiba LCD around 10% won’t work. If you install a Toshiba 3D touch panel into an LG LCD then 60% won’t work. Unfortunately, we don’t have any data for mixing Sharp LCDs or 3D touch panels"
"If the iPhone was calibrated for a Toshiba or Sharp LCD and you cross install between these 2 manufacturers there is roughly a 5% chance of bad touch. If the iPhone was originally calibrated for an LG LCD and you cross install with a Toshiba or Sharp LCD then there is a 50% chance of touch problems because LG’s sensitivity range distribution is very different to these 2 manufacturers. Without having the magic calibration box to tell the iPhone you’ve installed a different manufacturer’s LCD you are going to have trouble unless you install an LG LCD. This probably explains why, if you install an LCD and experience touch problems, then install another LCD and it works, you’d automatically assume a bad LCD. However, it is possible you’ve just switched manufacturer and got lucky. If you used the suspected bad LCD in the next repair it would more than likely work with no issues. "
"Magic calibration box" == ATS2 or whatever apple use for pairing
So, in summary, it is very easy to assume the LCD is faulty because it has touch problems when it is installed in an iPhone. However, there is the possibility that external factors could be causing the issue. It would be prudent to try and swap the LCD on a like for like basis and match the 3 letter code. If you do experience touch problems with a refurbished LCD then before returning it as faulty, try it in your next repair and it may just work.
More information on the subject can be found here. https://webuylcds.co.uk/2018/05/15/touch-compatibility-issues-with-iphone-7-7-8-8-screens/#:~:text=There%20are%20three%20companies%20who,LG%2C%20Toshiba%2C%20and%20Sharp