How old are these and how often / how long are they turned on? My OLED TV is over two years old now without any issues even though it gets frequent usage.

I have 3 LG OLEDs of all different generation and they all still go great. It is by far the best tv you can get vs other manufacturers.

You know your phone is OLED right? I'm assuming you left a still image on without the inbuilt screen refresher enabled or something? I remember seeing that way back in the early OLED days but not on good TVs in the last 8~ years.