Elementor has now updated the way it handles URLs in the URL control.
From v2.9.11 and on, Elementor will use the use wp_allowed_protocols() function to handle allowed URI protocols in links. These protocols are often used to create a deep-link (i.e. a direct link to an app via unique protocol) to a 3rd party application (such as mailto: or tel:)
This means that from this version, only protocols allowed by this WordPress function will be available.
Examples of allowed URI protocols: mailto:, tel:, sms:, etc…
If you wish to add another protocol to your website, you will need to alter the function that retrieves the list of allowed protocols, and add your own protocol.
function allow_additional_protocol( $protocols ){
$protocols[] = 'my-protocol';
return $protocols;
}
add_filter( 'kses_allowed_protocols' , 'allow_additional_protocol' );