The building is lying on uneven ground as it's built along the gradient of a slope. The building facing ofthis apartment directly faces aroad that slopes downwards. (see picture attachment)

In Fengshui sense, does thathave anyimplicationsthatwealth is draining away? Any difference inimpact to those living on the top floors as compared to those at the 1st and 2nd levels?

Frankly this is pretty common, and it depends.
In Singapore many estates have such a situation e.g. Siglap hill area, Hume Avenue, Yio Chu Kang, River Valley, Dunearn Road, Holland Rd areas.
In fact, just about anywhere. Thus, many factors including how the home was built.
In general, you are quite correct to say that earth luck (or poor luck) is usually strongest at the ground level.