GitHub Copilot is not using GPT-4 (yet)! I'm seeing a lot of people under the wrong impression.
For code completions it uses an improved version of Codex[1], and for chat beta (part of Copilot X), it uses 3.5-Turbo[2].
However, they're claiming to have "early adoption of OpenAI's GPT-4" for Copilot X on their marketing page[3], which is confusing/deceptive. To be fair, it's still in beta, but they should state outright what model you currently get if you sign up for it.
[1]: https://github.blog/2023-07-28-smarter-more-efficient-coding...
[2]: https://github.com/orgs/community/discussions/56975#discussi...