Codex models are no longer supported with a ChatGPT account

I have been using Codex on my Mac with Xcode for quite some time but only yesterday I started getting the error as such:

Codex encountered an error: {"detail":"The 'gpt-5.3-codex' model is not supported when using Codex with a ChatGPT account."}

This error seems to occur regardless of which version of Codex I select (5.2, 5.3, 5.4)

I am a ChatGPT Plus subscriber.

Is this a bug? Or is Codex no longer working at all for ChatGPT account holders regardless of tier?

If so, what are alternatives to getting Codex working again inside Xcode?