Wordpress cloned but frontend still displays http://old_wordpress_site

I have cloned my old_wordpress_site: files and db.

In the database I have replaced everything from old_wordpress_site into new_wordpress_site.

Wp-config.php on the new site has been updated with the credentials of the new database.

The admin dashboard is on the new url.

However, when I click visit site in admin dashboard, the frontend initially displays the new url and than switches to the old url after half a second.

What am I missing here?

Could it be that the front-end website is still connecting to the old database? That would puzzle me because config.php has been set to the new database.

I am stuck for two days now. Any help is welcome and much appreciated!