fix(ssr): avoid computed being accidentally cached before server render (#9688)

close #5300

Author: edison1105

packages/server-renderer/__tests__/ssrComputed.spec.ts

@@ -33,7 +33,6 @@ test('computed reactivity during SSR', async () => {
     // In both cases we need to fetch data.
     if (!msg.value) await store.fetchData()
 
-    expect(msg.value).toBe('hello world')
     return () => h('div', null, msg.value + msg.value + msg.value)
   })
 

packages/server-renderer/src/render.ts

@@ -144,7 +144,10 @@ function renderComponentSubTree(
     // perf: enable caching of computed getters during render
     // since there cannot be state mutations during render.
     for (const e of instance.scope.effects) {
-      if (e.computed) e.computed._cacheable = true
+      if (e.computed) {
+        e.computed._dirty = true
+        e.computed._cacheable = true
+      }
     }
 
     const ssrRender = instance.ssrRender || comp.ssrRender