Custom dynamic fields in mail

I’m creating some dynamic input fields in my form depending on an number that user put in another field.
These fields can be 1 or 20 or whatever amount and have different name like additional-field-1, additional-field-2 etc.
I want to get these fields in my mail body after user submit his form.
Tried to use a custom function in my themes functions.php by using this code

add_action('wpcf7_before_send_mail', 'additional_attendees');

function additional_attendees($wpcf7) {
 		
		$submission = WPCF7_Submission::get_instance();
				
		//GET VALUES
		$data = $submission->get_posted_data();		
}

but the get_posted_data() function doesn’t contain any of these fields, only the ones that i have used shorthands in my mail settings tab editor in wordpress.
So i guess i have to create some custom shorthands for them.
I’m trying to find a way to do that for infinite amount of custom fields but i’m not able to find anything.
Any help would be really appreciated.