Allow_squash_merge etc. in v3 PR response

In the PR API docs, the response has the following in the base.repo object:

      "allow_rebase_merge": true,
      "allow_squash_merge": true,
      "allow_merge_commit": true,

However, when I actually call the API, these parameters are not present. Note they are present on the repository API /repos/{org}/{repo}, but not the PR API /repos/{org}/{repo}/pulls/{id}.

Is there a way to get these parameters to show up in the PR API response that’s not documented? Or is this a documentation bug, where the PR docs are incorrectly re-using the response from the repository API, although it differs in practice?