Are you using an OEM/Original/Premium screen for the replacement? If so, keep on reading…
The 7/8 series screens are made by several manufacturers (Toshiba, LG, Sharp) and each phone is calibrated to the screen it has installed. It’s important not to mix and match screens. So for example, if your phone has an LG screen, you should replace it with an LG screen. The only way to know this is to look at the code on the backlight panel. Check out this blog (not affiliated) to learn more. However, even though you have a screen with the same code, it may still be a franken-screen. Lots of refurbish shops mix and match an LCD from one vendor, a touchscreen from another and possibly a backlight from another still. All you can identify is the backlight. This issue seems to be more prevalent on the Plus devices.
When replacing original quality screens, you should be using an ALS programmer to copy over the data from the original screen to the replacement screen. While this is primarily for the ALS sensor, it also helps with the Touch.
Curiously enough, the aftermarket screens don’t suffer from this issue at all. Unfortunately, they tend to have bland colours. A good alternative is an in-cell technology screen. They don’t have the touch issues and have great colours and are less expensive than OEM screens.