This is from a recent update, and I'm on macOS. I had to re-download it, not just update from within the app.

This new version has tabs for ChatGPT and Codex. The ChatGPT tab seems way less powerful; Codex is basically a coding agent with a UI and browser built in.

Pretty sure this is the old Codex app with the ChatGPT tab bolted on. It's great in some ways, but needs work in others.