Thanks for the report.  I'd like to confirm steps to reproduce:
1) evaluate:
var x = {arr: []};
console.log(x);     // This logs an object to the console, collapsed, showing text `{arr: Array(0)}`

2) evaluate:
x.arr.push('foo')

3) Expand the object previously logged, and see
> {arr: Array(0)}
  > arr: ["foo"]
  >_proto__: Object

If these are your bug reproduction steps, are you referring to the fact that DevTools shows "Array(0)" while its "arr" property is not length 0?

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	evaluatedJustNow.png 30.3 KB View Download

Seems similar enough.   Did it reproduce?

Thank you for providing more feedback. Adding requester "luoe@chromium.org" to the cc list and removing "Needs-Feedback" label.

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

I'm able to reproduce the mismatch between the preview of the object
`V {arr: Array(0)}`

and its property
`  > arr: ["foo"]`

If this is the behavior you are referring to, unfortunately this is intended behavior.  Whenever console.log() is called, a preview of the logged object is generated and logged to the console synchronously.  Property values seen in that preview are a snapshot in time.

However, when you expand an object in the console by clicking the triangle, DevTools retrieves the object's properties `at the time when you clicked expand`.  Properties at this time might be completely different than the properties at the time when the object was logged.

There are several other bugs that discuss this mismatch between logged-time and expanded-time properties here
https://bugs.chromium.org/p/chromium/issues/detail?id=50316

Please feel free to comment if you have further questions.