If you want to redirect in another way than using return. First of all you need to make sure you take care of all of the saving of everything in your pre_save_post filter. If there are additional values that ACF needs to update, this will not happen if you do not return from your function. The reason I say this is that you need to exit completely after performing the redirect
wp_redirect( home_url() . '/sign-in/?new_user=true&user_email=' . $candidate_email );
exit;
Would it be possible to generate the return value for acf_form() before calling it and set the ‘return’ value based on whether or not it’s a new user?
