Version

3.2.4

Reproduction link

https://codesandbox.io/s/intelligent-gauss-uveoj?file=/src/components/HelloWorld.vue

Steps to reproduce

click “Change” button，

What is expected?

data change, execute console.log("modify");

What is actually happening?

watch does not work

it's still the same object returned from the watcher's first argument, so it's correct that its not triggering.

You might be looking for the deep: true option on that watcher.