TypeScript's type acquisition can infer what types should be added based on filenames in a project. This means that having a file like jquery.js in your project would automatically download the types for JQuery from DefinitelyTyped.

You can disable this via disableFilenameBasedTypeAcquisition.

{
  "typeAcquisition": {
    "disableFilenameBasedTypeAcquisition": true
  }
}

{
  "typeAcquisition": {
    "disableFilenameBasedTypeAcquisition": true
  }
}