Most mobile phones are using OLED technology nowadays, which has the advantage of consuming less battery and being physically thinner due to the removal of the backlight panel, which is present in the older LCD screen. This includes iPhone X, and the almost all the newer Samsung models. As with everything, there can always be a potential issue. For OLED screen, the issue that can occur is the burn-in problem.
Burn-in occurs when a part of the screen image remains as a ghostly background regardless of what type of image is showing on the display screen. While OLED burn-ins are not very common, it can certainly occur. On Google Pixel’s website, it states that burn-in can happen when the same image is on a phone screen for a prolonged period at a high brightness level. As for Apple website, it mentions that they had designed their phones to reduce the OLED burn-in, but it is something that can still occur.
To avoid the chance of experiencing screen burn-ins, try not to leave your phone on at the same image for a long time. Also, it is best not to operate your phone at maximum brightness all the time.
There is a difference between actual burn-in and image retention. While some websites might use these terms interchangeably, there are not the same. Imagine retention is a temporary occurrence, while burn-in is permanent. It never goes away on its own. Image retention is the term to describe the occurrence when parts of an image remain on screen even after the image is supposed to be gone. For example, if you are watching Avengers and Thors swings his hammer, the hammer should be moving. If the image of the hammer is suddenly stuck on your phone, that means your phone screen is experiencing image retention. In most cases, image retention issue would go away on its own.
Phone screen burn-ins are usually not covered under standard warranty. According to LG, most manufacturer warranty does not support burn-ins. Sony mentions that their warranty covers manufacturing defects. However, as burn-ins are considered as an issue related to consumer use rather than a manufacturing defect, this issue is not covered under standard warranty.
As such, the best practice, as mentioned earlier, is to try to avoid the possibility of screen burn-ins in the first place. It is not hard at all. First of all, try not to have the habit of turning your screen brightness to the maximum all day. Besides increasing the chance of burn-ins, it drains your battery quickly anyway. So perhaps, you can consider setting your phone screen brightness to somewhere around 50%-80% such as 80% when it is very sunny outside and 50% when you are indoor. Secondly, do not leave your phone on at the same image for a long time.
If you think you are experiencing screen burn-ins, wait a while and see if goes away. If it goes away after a few minutes, what you have experienced is just image retention and not actual burn-in. However, if it does not go away, your phone is likely to be suffering screen burn-in. You can get your phone screen repaired or replaced at a mobile phone shop to solve this problem.