issue fixed

packages/volto/news/2837.bugfix

@@ -0,0 +1 @@
+Resolved an issue where block restrictions only applied to top-level blocks, allowing restricted blocks (e.g., Title) in nested contexts. The system now enforces restrictions across all block levels, preventing duplicates throughout the page.

packages/volto/src/config/Blocks.jsx

@@ -247,6 +247,29 @@ const groupBlocksOrder = [
   { id: 'common', title: 'Common' },
 ];
 
+const checkBlockRestriction = ({ properties, block }) => {
+  const checkBlockRecursively = (blocks, blockId) => {
+    if (!blocks || typeof blocks !== 'object') return false;
+    return Object.entries(blocks).some(([_uid, blockData]) => {
+      if (!blockData) return false;
+      if (blockData['@type'] === blockId) {
+        return true;
+      }
+      if (
+        (blockData.blocks && blockData.blocks_layout) ||
+        (blockData.data &&
+          blockData.data.blocks &&
+          blockData.data.blocks_layout)
+      ) {
+        const nestedBlocks = blockData.data?.blocks || blockData.blocks;
+        return checkBlockRecursively(nestedBlocks, blockId);
+      }
+      return false;
+    });
+  };
+  return checkBlockRecursively(properties.blocks, block.id);
+};
+
 const blocksConfig = {
   title: {
     id: 'title',
@@ -256,10 +279,7 @@ const blocksConfig = {
     view: ViewTitleBlock,
     edit: EditTitleBlock,
     schema: BlockSettingsSchema,
-    restricted: ({ properties, block }) =>
-      properties.blocks_layout?.items?.find(
-        (uid) => properties.blocks?.[uid]?.['@type'] === block.id,
-      ),
+    restricted: checkBlockRestriction,
     mostUsed: false,
     blockHasOwnFocusManagement: true,
     sidebarTab: 0,