Check FlashErased or Readout InternalFlash ECC on STM32H7

I'm working on the STM32H7 series, and in my scenario the data to be written might be the erased-state byte (0xFF) all over the flashword. In this case I'm unsure whether or not the ECC may change.

What is the idiomatic way of checking if the bytes have been written or not? Observing the internal flash memory, is it possible to deduce if a flashword was written, even if it contains only 0xFF ?

Thanks in advance