If your eyes are sensitive to flickering displays, then it may be best to avoid Samsung's latest flagship. The Galaxy Note 9 display flickers at a frequency of 227 Hz that could potentially cause headaches and tiredness. The practice, known as pulse-width modulation, is rarely seen on smartphones.
https://www.notebookcheck.net/Take-caution-Samsung-Galaxy-Note-9-display-flickers-by-design-and-could-cause-eyestrain.325712.0.html