Funda & brochure m2 different from official meetrapport m2 ?

Hi all we just visited an apartment with external garden house. In the official documentation it is mentioned the place has 68m2 + 10m2 storage / work space.
But on funda it is mentioned 78m2 living space and the funda meetrapport mentions this external space as living space. The official meetrapport accessed after viewing mentions it as GOEB. Which means there are two conflicting floor plans one advertised and one officially done.
Makes a huge difference in my opinion on current and future value what do you think and is this something that happens regularly ?