Any device that uses an OLED screen panel will definitely be at risk of facing burn in problems on the screen. Burn In is a problem where the image on the screen "burns" so that it remains displayed even after changing to another image. This issue plagues the majority of early generation OLED TVs. Samsung devices running One UI 5 don't suffer from this problem because the software has a feature to randomly move pixels as a protection method.
Android Authority reports that One UI 6 may not provide this protection feature based on a post raised by u/dragosslah on Reddit. Without this protection, Samsung devices running One UI 6 can lose color, become faded and then can experience dead pixels. Here is a test done to check whether this protection is there or not;
Take a screenshot with the status bar (displaying battery and cellular signal strength) still visible.
Rotate the device to landscape mode and then back to portrait about 5 times (a lot of movement on the screen content will activate this feature as it should)
Open the screenshot and see if the image will be layered or not.
If the image is layered it means there is protection and vice versa if the image is not layered.
This issue, however, is seen as inconsistent because it only occurs on the status bar. On the navigation bar side this issue does not occur. It is expected that Samsung will distribute an update so that the screen of the user's device can last longer after updating to One UI 6.