It has been observed, that for at least one user, public holidays are displayed, incorrectly.
the actual holiday is represented colored as a regular weekend day, while the day after the public holiday is colored in the color used to represent public holidays and when clicked on shows the name of the holiday in the description.

It is currently unclear, whether the work hours are also calculated with 2 holidays (the actual public holiday + the day after), or it is just a matter of presentation.