Updating a Key Creates a New Object Instead of Modifying the Existing One

[BlueBeret]

Prerequisites

• I have searched the existing issues
• I understand that providing a SSCCE example is tremendously useful to the maintainers.
• I have read the documentation
• Ideally, I'm providing a sample JSFiddle, Codesandbox.io or preferably a shared playground link demonstrating the issue.

What theme are you using?

core

Version

^5.9.0

Current Behavior

When an object has additional properties and default values, updating it creates a new object with the updated key.

Expected Behavior

The expected behavior is to update the key on the existing object instead of creating a new object with that key.

Steps To Reproduce

demo: https://jam.dev/c/c0f3a17a-7ee7-4e25-8cb7-7f1463ffd972
source: rjsf-team-playground

1. update the key
2. instead of updating current object it creates new object with the new updated key

Environment

- OS: Fedora Linux 41
- Node: v16.20.2
- npm: 8.19.4

Anything else?

demo: https://jam.dev/c/c0f3a17a-7ee7-4e25-8cb7-7f1463ffd972
source: rjsf-team-playground

[nickgros]

@BlueBeret Can you double-check your playground link? We're having trouble reproducing it. The object appears update as expected.

You could also share your browser/version and locale, as sometimes those are related to bugs like this.

[heath-freenome]

@BlueBeret I agree with Nick. This is what I'm seeing on Chrome.

Screen.Recording.2026-01-30.at.12.51.16.PM.mov