fix(suspense): In nested slots suspense should return to pending state

packages/runtime-core/__tests__/components/Suspense.spec.ts

@@ -4,6 +4,7 @@
 
 import {
   type ComponentOptions,
+  type ComponentPublicInstance,
   Fragment,
   KeepAlive,
   Suspense,
@@ -16,6 +17,7 @@ import {
   onUnmounted,
   ref,
   render,
+  renderSlot,
   resolveDynamicComponent,
   serializeInner,
   shallowRef,
@@ -1730,6 +1732,55 @@ describe('Suspense', () => {
     await Promise.all(deps)
   })
 
+  // #5247
+  test('In nested slots suspense should return to pending state', async () => {
+    const id = ref('1')
+    const Async = defineAsyncComponent({
+      render() {
+        return h('div', `async`)
+      },
+    })
+    const onPending = vi.fn()
+    const wrapper = {
+      setup() {
+        return (ctx: ComponentPublicInstance) =>
+          h(
+            Suspense,
+            { onPending },
+            {
+              default: () => [renderSlot(ctx.$slots!, 'default')],
+              fallback: () => h('div', 'fallback'),
+            },
+          )
+      },
+    }
+
+    const Parent = {
+      setup() {
+        return () =>
+          h(wrapper, null, {
+            default: () => h(Async, { id: id.value }),
+          })
+      },
+    }
+
+    const root = nodeOps.createElement('div')
+    render(h(Parent), root)
+
+    expect(serializeInner(root)).toBe(`<div>fallback</div>`)
+    await Promise.all(deps)
+    await nextTick()
+    expect(serializeInner(root)).toBe(`<div id="1">async</div>`)
+    expect(onPending).toHaveBeenCalledTimes(1)
+
+    id.value = '2'
+    await nextTick()
+    await Promise.all(deps)
+    await nextTick()
+    expect(serializeInner(root)).toBe(`<div id="2">async</div>`)
+    expect(onPending).toHaveBeenCalledTimes(2)
+  })
+
   describe('warnings', () => {
     // base function to check if a combination of slots warns or not
     function baseCheckWarn(

packages/runtime-core/src/components/Suspense.ts

@@ -1,5 +1,6 @@
 import {
   Comment,
+  Fragment,
   type VNode,
   type VNodeProps,
   closeBlock,
@@ -333,7 +334,13 @@ function patchSuspense(
       }
     }
   } else {
-    if (activeBranch && isSameVNodeType(newBranch, activeBranch)) {
+    if (
+      activeBranch &&
+      isSameVNodeType(newBranch, activeBranch) &&
+      // #5247 In the nested slot, the slot will be compiled into a fragment,
+      // and the suspense should return to the pending state at this time
+      !(newBranch.type === Fragment && activeBranch.type === Fragment)
+    ) {
       // root did not change, just normal patch
       patch(
         activeBranch,