Are you using the Python API or Android Things?
Sounds like it's using one of the diagonals not typical on a 7-segment display to make a 5 that's stylistically different from a capital S.
In the code, the 5 is
Versus 'S' which is
Although the S doesn't look traditional either, since it's got 6 bits set, not 5 (top, top left, middle, bottom right, bottom)
I don't have one to look at right now, so a picture may help!