VisitsSummary.getVisits not working for specific days

I’m querying Matomo using Postman, for example, like:

{{base_url}}/index.php?method=VisitsSummary.getVisits&idSite=21&period=range&date=2023-07-07,2023-07-07&module=API&format=JSON&token_auth={{matomo_token}}

This request is not working. I get a timeout after a while.

However, if I do this request instead:

{{base_url}}/index.php?method=VisitsSummary.getVisits&idSite=21&period=range&date=2023-07-06,2023-07-06&module=API&format=JSON&token_auth={{matomo_token}}

I get an answer like this:

{
    "value": 291
}

What could be the reason for the first request to timeout?

The only thing that changes between requests in the range.