Differences in object sizes in Illustrator 27

Since Illustrator 27.0 I have a problem with the size of objects:

E. g. I draw a rectangular with 100 x 100 px. When I click on this rectangular and look in the check box for the size there is shown 101 x 101 px. (The same in mm: I create a rectangular in 10 x 10 mm and the check box says 10,1 x 10,1 mm.)

Big question: Which size is the correct one? The size that I have drawed or the size shown in the check box?

In Illustrator 26 the size shown in the check box was the same like I have drawn it.