fix: validate newly entered phone numbers

src/Service/ParticipantDataPrefiller.php

@@ -67,6 +67,7 @@ class ParticipantDataPrefiller
         $applicant->dateOfBirth = $prepopulated->dateOfBirth;
         $applicant->email = $prepopulated->email;
         $applicant->mobile = $prepopulated->mobile;
+        $applicant->loadedMobile = $prepopulated->loadedMobile;
         $applicant->address = $prepopulated->address;
         $applicant->height = $prepopulated->height;
         $applicant->weight = $prepopulated->weight;