Firestore Security Rules - How can I check that a field is/isn't being modified?

Question

For the life of me, I cannot understand why the following is resulting in a false for allowing writes. Assume my users collection is empty to start

Answer 1

Since reference to writeFields in documentation has disappeared, I had to come up new way to do what we could do with writeFields.

function isSameProperty(request, resource, key) {
    return request.resource.data[key] == resource.data[key]
}

match /myCollection/{id} {
    // before version !request.writeFields.hasAny(['property1','property2','property3', 'property4']);
  allow update: isSameProperty(request, resource, 'property1')
    && isSameProperty(request, resource, 'property2')
    && isSameProperty(request, resource, 'property3')
    && isSameProperty(request, resource, 'property4')
  }