I have experienced display discoloration issue after April 2020 security update. My phone was working fine and abruptly my display got disturbed. Now black colour is not completely black but a little gray. Also while watching videos display of black has some tinted effect. This change of colour is more visible when brightness is low. Anybody having any idea what could be the possible reason or how to fix it?
The security update might be a coincidence (it is very unlikely that sort of update changed any UI looks etc.) How old is the phone? It might need to be returned or have the screen replaced.