Google search date from or date after?

I want to return the results only before or after a certain date.

I read here that it is just to use before:YYYY-MM-DD

But when I try, for example corona before:2020-02-30, I see that most of the results date from today.

How can I filter the search results for after / before a date using a search operator?


Strangely after/before the operators make seem to work sometimes

For example.

It works

corona before:2010-01-01

But it does return news / articles today (later than 2020-02-30)

corona before:2020-02-30

Note: for good measure, I tried corona before:2020-30-02, but it returns the same – news today when it shouldn't