A little confusing

I am doing a test booking on my page. When selecting the Calendar icon, the "legend" shows Blocked (red) and Selected (grey) days. But holidays are also grey and they are neither in the legend nor a selected day. Isn't that confusing to a Booker?

https://www.jimthorpevacationrentals.com/book

Holidays are blue.

mine looked greyish. But it seems "Holidays" with a blue box should be added to the legend at bottom.