the check suite payload format was incorrect
here is an example pull requests list

{
  "pull_requests": [
    {
      "url": "https://api..com/repos/tim-thacker-nullify/test/pulls/49",
      "id": 1627588747,
      "number": 49,
      "head": {
        "ref": "dast",
        "sha": "0fd21c48c83560c7ca5aee52245374a9544be1ee",
        "repo": {
          "id": 675442557,
          "url": "https://api..com/repos/tim-thacker-nullify/test",
          "name": "test"
        }
      },
      "base": {
        "ref": "main",
        "sha": "5434fdea861a950a4ac02b7377fbf51d7a2eb95a",
        "repo": {
          "id": 675442557,
          "url": "https://api..com/repos/tim-thacker-nullify/test",
          "name": "test"
        }
      }
    }
  ]
}

coverage: 88.765%. remained the same
when pulling 4b4d7a1 on Nullify-Platform:fix-check-suite-payload
into 53694f8 on go-playground:master.