only in patch2:
unchanged:
--- a/core/modules/search/search.post_update.php
+++ b/core/modules/search/search.post_update.php
@@ -22,3 +22,14 @@ function search_post_update_block_page(&$sandbox = NULL) {
       return $block->getPluginId() === 'search_form_block';
     });
 }
+
+/**
+ * Mark everything for reindexing after diacritics removal rule change.
+ */
+function search_post_update_reindex_after_diacritics_rule_change() {
+  $search_page_repository = \Drupal::service('search.search_page_repository');
+  foreach ($search_page_repository->getIndexableSearchPages() as $entity) {
+    $entity->getPlugin()->markForReindex();
+  }
+  return t("Content has been marked for re-indexing for all active search pages. Searching will continue to work, but new content won't be indexed until all existing content has been re-indexed.");
+}