isDirty is true for objects inside fieldArray elements before changes

Describe the bug When using useFieldArray with an array of objects, containing nested objects, dirtyFields will be true for the nested object as soon as it is added, before any of its children have been changed.

To Reproduce Steps to reproduce the behavior:

1. Go to the below Codesandbox
2. No fields are currently dirty (as shown in the screenshot below)
3. Click ‘Add User’
4. Dirty fields is now:

[
  {
    "details": true // Expected: false
  }
]

1. Fill out either (or both) of the inputs
2. Dirty fields is now (if both filled out):

[
  {
    "details": {
      "first": true,
      "last": true
    }
  }
]

Codesandbox link (Required) https://codesandbox.io/s/infallible-wave-kg5z4?file=/src/App.js

V7.6.7

Expected behavior I would expect either of the following:

• details to be false - as I have not modified any of its child fields yet
• details to be { first: false, last: false } - as it should know about the child fields already as they have been registered

Screenshots

Desktop (please complete the following information):

• OS: Windows 10
• Browser Chrome
• Version 90

Additional context N/A

[bluebill1049]

updated: https://github.com/react-hook-form/documentation/commit/bbd8afb5805bb5f44adeaa2decdb39b16463b494

[bluebill1049]

Is it worth sticking that in the docs with a brief explanation? Maybe it will help someone else?

definitely a good idea. I will get that updated.