just today, MS announced that gpt-5.3-codex will become Copilot’s new base model. It is also the first LTS model that will be supported until 2027.

https://github.blog/changelog/2026-03-18-gpt-5-3-codex-long-...

That's github copilot though, which is different (gh is msft, but here you have the option to choose other models too). Their regular copilot app and the one on windows still uses oai as their base model, which can hurt oai, if they choose to move away from it