I have just been informed by Samsung (useful to note that it has taken 4 months to get an answer) that as part of the Android 10 upgrade, the Amoled Display feature in settings/display/screen mode has been removed by the developers. The replacement when I go into settings/display/screen mode is now just "Normal" and " Vivid".
I do find it strange the developers have decided we have to have this removed when it was a feature the camera sold for! In addition, the new A51 and A71 plus other ranges currently all sell with the Amoled Display.
I really don't understand this decision.