The codecov config lives at https://github.com/python/cpython/blob/master/.github/codecov.yml and the docs for the file are at https://docs.codecov.io/docs/codecov-yaml. Specifically, the comment feature is covered at https://docs.codecov.io/docs/pull-request-comments and the status check is at https://docs.codecov.io/docs/commit-status.

Nothing has changed in the config, though, so it might be a change related to https://docs.codecov.io/docs/codecov-yaml#section-can-i-name-the-file-codecov-yml and thus the file path to the config might need to be added to the upload step in the following files:

1. https://github.com/python/cpython/blob/master/.github/workflows/coverage.yml
2. https://github.com/python/cpython/blob/master/.travis.yml
3. https://github.com/python/cpython/blob/master/.azure-pipelines/posix-steps.yml#L52

(I would submit a PR myself but I'm still digging myself out from under email after vacation.)