How to find disabled azure services in azure devops project

This is an feature in Project Settings. I checked the related REST API and Azure CLI for Team Projects, however I did not find any available interface can list the info about enabled / disabled services, also no available interface to enabled / disabled services.

So, I think your question is more like a feature request. I recommend that you can report the feature request to Developer Community.

[UPDATE]

I found below API from the Network logs of the web browser (press F12). I have tested this API on my side, it should be the one you are looking for.

• Request URI:

POST https://dev.azure.com/{Organization_name}/_apis/FeatureManagement/FeatureStatesQuery/host/project/{Project_id}?api-version=4.1-preview.1

• Request Body:

{
    "featureIds": [
        "ms.vss-work.agile",  // Boards
        "ms.vss-code.version-control",  // Repos
        "ms.vss-build.pipelines",  // Pipelines
        "ms.vss-test-web.test",  // Test Plans
        "ms.feed.feed"  // Artifacts
    ],
    "featureStates": {},
    "scopeValues": {
        "project": "{Project_id}"
    }
}

• Response Body:

{
    "featureIds": [
        "ms.vss-work.agile",
        "ms.vss-code.version-control",
        "ms.vss-build.pipelines",
        "ms.vss-test-web.test",
        "ms.feed.feed"
    ],
    "featureStates": {
        "ms.vss-work.agile": {
            "featureId": "ms.vss-work.agile",
            "scope": {
                "userScoped": false,
                "settingScope": "project"
            },
            "state": "disabled"
        },
        "ms.vss-code.version-control": {
            "featureId": "ms.vss-code.version-control",
            "scope": null,
            "state": "enabled"
        },
        "ms.vss-build.pipelines": {
            "featureId": "ms.vss-build.pipelines",
            "scope": null,
            "state": "enabled"
        },
        "ms.vss-test-web.test": {
            "featureId": "ms.vss-test-web.test",
            "scope": null,
            "state": "disabled",
            "reason": "\"Test Plans\" is off because the \"Boards\" feature is off. In order to manage \"Test Plans\", you must turn on \"Boards\".",
            "overridden": true
        },
        "ms.feed.feed": {
            "featureId": "ms.feed.feed",
            "scope": null,
            "state": "enabled"
        }
    },
    "scopeValues": {
        "project": "{Project_id}"
    }
}

The right name of the features are:

ms.vss-build.pipelines  [Azure Pipelines]
ms.vss-test-web.test [Test Plans]
ms.vss-work.agile [Azure Boards]
ms.vss-code.version-control [Azure Repos]
ms.azure-artifacts.feature [Azure Artifacts]