It is unclear what this new Diamond OLED trademark refers to since there are so many devices mentioned in the patent. The two best guesses would be TV screens for the upcoming QD-OLED models launching in the second half of 2021 or an upgraded foldable OLED display with Diamond pixels for foldable smartphones like the Galaxy Z Flip 3.
https://www.notebookcheck.net/Samsung-files-for-Diamond-OLED-patent-in-the-UK.533412.0.html