Proposed changes not showing as expected, diff is missing

What version of Codex is running?

0.20.0

Which model were you using?

gpt 5

What platform is your computer?

Ubuntu 24.04

What steps can reproduce the bug?

<img width="2364" height="312" alt="Image" src="https://github.com/user-attachments/assets/a247ef22-5a79-4052-8855-e2b801d83daf" />

As you can see from the screenshot, the proposed changes are not formated, the diff is missing and there is no colors. It's impossible to understand what's happening.

What is the expected behavior?

Please see how claude cli and gemini cli are showing the changes and fix this. Thank you.

What do you see instead?

just a patch of text that is unreadable

<img width="2364" height="312" alt="Image" src="https://github.com/user-attachments/assets/a247ef22-5a79-4052-8855-e2b801d83daf" />

Additional information

_No response_