Resolving a GitHub Issue from a Project Card via the RESTful SDK - github

Question

I'm using octokit (https://octokit.github.io/rest.js/v18#projects-list-cards) to interact with my Project and Issues in my repo. I have the project_cards in a list, but I'd like to make some changes to the labels on the issue when I move from column to column.
As near as I can tell (https://docs.github.com/en/rest/reference/projects#list-project-cards), the only way to get the issue number is to manually parse the content_url field:
[
{
"url": "https://api.github.com/projects/columns/cards/1478",
"id": 1478,
"node_id": "MDExOlByb2plY3RDYXJkMTQ3OA==",
"note": "Add payload for delete Project column",
"creator": {
"login": "octocat",
"id": 1,
"node_id": "MDQ6VXNlcjE=",
"avatar_url": "https://github.com/images/error/octocat_happy.gif",
"gravatar_id": "",
"url": "https://api.github.com/users/octocat",
"html_url": "https://github.com/octocat",
"followers_url": "https://api.github.com/users/octocat/followers",
"following_url": "https://api.github.com/users/octocat/following{/other_user}",
"gists_url": "https://api.github.com/users/octocat/gists{/gist_id}",
"starred_url": "https://api.github.com/users/octocat/starred{/owner}{/repo}",
"subscriptions_url": "https://api.github.com/users/octocat/subscriptions",
"organizations_url": "https://api.github.com/users/octocat/orgs",
"repos_url": "https://api.github.com/users/octocat/repos",
"events_url": "https://api.github.com/users/octocat/events{/privacy}",
"received_events_url": "https://api.github.com/users/octocat/received_events",
"type": "User",
"site_admin": false
},
"created_at": "2016-09-05T14:21:06Z",
"updated_at": "2016-09-05T14:20:22Z",
"archived": false,
"column_url": "https://api.github.com/projects/columns/367",
"content_url": "https://api.github.com/repos/api-playground/projects-test/issues/3",
"project_url": "https://api.github.com/projects/120"
}
]
This seems pretty surprising to me, am i missing something? I'm just looking to figure out what the underlying issue number is so that I can do some manipulation of the labels.