Does anyone understand this? The region is correctly defined as the first unit square, but it is displayed with the corners cut off:
Block[{reg}, Column[{
reg = Region[ImplicitRegion[0 <= x <= 1 && 0 <= y <= 1, {x, y}]],
Element[{1, 1}, reg]
}]]
If you draw the region with RegionPlot, everything is fine:
RegionPlot[0 <= x <= 1 && 0 <= y <= 1, {x, 0, 1}, {y, 0, 1},
ImageSize -> Small]