[BUGFIX] Fix setting of the page id in FormsFinisher

Classes/Finisher/Forms/FormsFinisher.php

@@ -136,6 +136,7 @@ class FormsFinisher extends AbstractFinisher {
 		$site = GeneralUtility::makeInstance(SiteFinder::class)->getSiteByPageId((int) $GLOBALS['TSFE']->id);
 		$siteLanguage = $site->getLanguageById($languageId);
 		$mailTemplateService->setSiteLanguage($siteLanguage);
+		$mailTemplateService->setPid($site->getRootPageId());
 
 		$mailToAddresses = trim((string) $this->parseOption('mailTo'));
 		if ($mailToAddresses !== '') {