STM32H743VGT6 should be 1M of FLASH, STM32H743VIT6 being 2M of FLASH
But ST might not make different silicon chips to go into the two parts.
What they might do is, during production, test the FLASH memory and if there is any doubt about any of it, they will map out the dodgy bit and only sell it as a 1M part.
If they have more demand for the 1M part than those parts that test as bad, they might sell some with 2M of FLASH fully available. Or they might have a way of "turning off" the unwanted-but-supposedly-good area of FLASH.
If demand for the 1M parts really hots up, they will actually go to the effort of producing a mask-set that only has 1M of FLASH (plus a little more for luck) so many of the 1M parts won't have started with 2M of FLASH. This would be a significant capital investment for ST, so they might not initially go down this route.
ST have supplied you with a part that they guarantee has 1M of good FLASH. They make no promises about what else you might find in there. Any extra *might* be good FLASH, but part of it might be FLASH that works initially but then does not store for the specified lifetime or over full temperature range.
Regards,
Danish
