gpt-5.3-codex stopped working with ChatGPT account and disappeared after update

What version of the Codex App are you using (From “About Codex” dialog)?

26.506.31421 before update; after update unknown

What subscription do you have?

ChatGPT Plus

What platform is your computer?

Windows x64

What issue are you seeing?

The gpt-5.3-codex model was working for me for two days in the Codex Desktop App using my ChatGPT account.

Then it suddenly stopped with this error:

The 'gpt-5.3-codex' model is not supported when using Codex with a ChatGPT account.

Before updating Codex Desktop, gpt-5.3-codex was still visible in the model selector but failed when submitting requests.

After updating Codex Desktop, gpt-5.3-codex and gpt-5.2 disappeared from the model selector. The only visible models now are:

• GPT-5.5
• GPT-5.4
• GPT-5.4-Mini

<img width="1165" height="529" alt="Image" src="https://github.com/user-attachments/assets/4e6b5be6-bfb7-486a-8ff3-f84ddfb9419e" />

<img width="868" height="400" alt="Image" src="https://github.com/user-attachments/assets/ee58ef58-25cc-4d15-a746-1b8153dd1c4b" />

<img width="1894" height="510" alt="Image" src="https://github.com/user-attachments/assets/6425c9f7-bfc5-4299-8f93-701fb0f4a681" />

What steps can reproduce the bug?

1. Open Codex Desktop App on Windows.
2. Sign in using a ChatGPT account with ChatGPT Plus.
3. Before the update, select gpt-5.3-codex.
4. Submit any request.
5. The request fails with:

The 'gpt-5.3-codex' model is not supported when using Codex with a ChatGPT account.

1. Update Codex Desktop App.
2. Open the model selector again.
3. gpt-5.3-codex and gpt-5.2 are no longer visible.

What is the expected behavior?

If gpt-5.3-codex is still supported for ChatGPT account users, it should continue working and remain visible in the model selector.

If it is no longer supported for my account or plan, the app should clearly explain that this is an entitlement, plan, routing, rollout, or intentional availability change.

The app should not show a model that fails with “not supported when using Codex with a ChatGPT account.”

Additional information

Feedback ID:
019e7e29-8154-7473-b08d-be28bdace1a7

Auth method: ChatGPT account
Plan: ChatGPT Plus
App version before update: 26.506.31421

Please confirm whether this is an entitlement issue, server-side routing issue, intentional availability change, or temporary rollout/incident.