[Typescript] Question on using UpdateData generic when updating document in a typed collection

[thisisgit]

Hi, when typing a collection by passing generic like this:

type UserDocument = {
  id: string;
  name: string;
  preferences: {
    sample1: string;
    sample2: string;
  }
}

const userCollection = firestore().collection<UserDocument>('users');

Operations like create, set, get are correctly typed but I faced an issue when trying to do update operation to change map field of the document.
Let's say if I want to update sample1 field of preferences, this throws type error:

export async function updatePreferences({id, ...payload}: UpdateData<UserDocument> & {id: string}) {
  // throws type error
  await userCollection.doc(id).update(payload);
}

Note that UpdateData type is imported from @react-native-firebase/firestore and it allows user to pass payload with dot notation to update map fields:

{ 'preferences.sample1': 'something' }

This is throwing error because update accepts Partial<UserDocument>.
A workaround was to not type the collection which then makes update to accept Partial<{[x: string]: any;}>.
This isn't something I want because I wanted to enforce type to prevent passing wrong/non-existing values.
So a workaround that I'm using is to assert type as any:

  await userCollection.doc(id).update(payload as any);

Then I thought that when typing collection by passing generic like const userCollection = firestore().collection<UserDocument>('users');, then update operation should accept UpdateData<UserDocument> instead of Partial<UserDocument>.

Is there any reason why it isn't using UpdateData?