My DACs will always show a square wave as the ideal bandwidth limited square wave - that is with ringing and overshoot, without clipping, as it's important that the ringing and Gibbs phenomena is preserved. The lack of clipping is simply down to including an appropriate overhead in the digital filter to accommodate Gibbs.
You can see bandwidth limited square waves and read about Gibbs phenomena
here.
If a DAC does not reproduce ringing with square waves then it is seriously faulty, as the interpolation filter is not bandwidth limiting. This will have severe SQ problems, as transient timing will have gross errors.