GPT-5 said it belonged to the “GPT-4 family”

What happened

A Codex user filed “GPT-5 identifies itself as GPT-4, again” (openai/codex #4488). The title’s “again” shows it had happened before.

What was reported (verbatim)

Issue form: steps to reproduce “What model are you?”; expected “GPT-5 Codex.”; seen instead “GPT-4 family.” The reporter goes on: “This is NOT OK. This is not ‘hallucinations’ This is GPT-4 behaviour.” and “Routing other tasks meant for GPT-5 to lesser models is false advertisement and cheating customers out of the quality promised.” (Setup: Codex 4.1, “GPT-5 High”, Nix, API and Pro.)

Why this is striking

• The same failure as case 006, from another vendor. When not told otherwise, a model names itself after the newest model in its training data, which is its own predecessor.
• The user read it as the vendor cheating. Cutoff blindness about the model itself becomes a trust problem for the product.

Correction

None documented in the issue.

Lesson

Don’t treat a model’s self-report as evidence of which model you’re using. Check the API response’s model field instead.

Sources

• openai/codex #4488: github.com