I recently bought a "new" OLED65C8 and it indicated a "Total Power On Time" of 3999 hours. I contacted LG Support via chat for an explanation and they abruptly terminated the chat, without explanation, when I asked how accurate this metric was and what tolerances it has.
I suppose this metric could be an artifact from when the OS was imaged onto the new TV. However, in the worst case, a shady retailer could be selling used/refurbished product as new. But, if I'm not mistaken, this metric can be reset via the service panel. If so, you'd think the shady individual would also reset the hours to zero.
I'll post again if I find any thing that is significant.