Text size inside button is not upto scale, as displayed in demo

[generalpy101]

I am using bootstrap4-toggle with MDBootstrap v4.5. When I try to create toogle swith with following code :
<input type="checkbox" checked data-toggle="toggle" data-on="View" data-off="Edit" data-onstyle="success" data-offstyle="danger" data-size="sm" />

Text size is not upto scale. It has the same problem in text size for normal or xs size.

Above is for sm size

Above image is for xs size

Normal size