Do you really think they mean they’ve been using mythos
The SOTA: Fable, GPT 5.6 Sol, Opus 5
The "enterprise admin did not turn on the new models": Opus 4.8, GPT 5.5
The "I love hallucinated garbage": Sonnet, Qwen 3.6, GPT 5.4 mini, GPT 5.3 Codex, etc.
Results vary widely
Before that, Gemini 3 Pro in Antigravity.
I have no experience with GPT 5.3 beyond seeing the nightmares colleagues produced in their MRs with GPT 5.3 Codex. It could be that they had the distilled 5.3 Codex Spark selected, I am not sure.