OVF focus frame burn-in -xpro3

Hi everyone,

Recently, I noticed a burn-in on the EVF at the focus frame area, perhaps due to having it for prolonged period at the centre while using the OVF.
Probably more apparent for my use case; near to 100% of the time using OVF.

It is not obvious, just a slightly dim squarish outline while in the EVF. Does it happened to the pro1 & 2? Or is it a characteristic of OLED?

Thanks