Placeholder for numbers doesn't work

How Do I...
#1 
<select data-placeholder="2020">
  <option></option>
  <option>1990</option>
  <option>1991</option>
  <option>1992</option>
</select>

When I pass a number to the date attribute, it doesn’t appear in the placeholder, why?

#2

This seems to be a bug. However, you can work around it by including a space as the first character of the placeholder: <select data-placeholder=" 2020">. As far as I can tell, the leading space is not displayed on screen.

#3

Thank you very much…