SharePoint Online SP.FieldUserValue.get_email() always returns NULL.

Since last week, SP.FieldUserValue.get_email() has been returning null for all users in Person or Group fields.
This occures when I use getItems method. For example:

var listName = "MyList";
var context = SP.ClientContext.get_current();
var web = context.get_web();
var list = web.get_lists().getByTitle(listName);
var query= new SP.CamlQuery();
var items = list.getItems(query);
context.load(items);
context.executeQueryAsync(()=>{
    var enumerator = items.getEnumerator();
    while (enumerator.moveNext()) {
    var item = enumerator.get_current();
    var fldValues = item.get_fieldValues();
    console.log(fldValues["Editor"].get_email())
}
});

I haven’t been able to find any information about changes related to this behavior. We’ve been using the Email property of user fields for years without any issues, and it has always worked as expected. It's documented here:
https://learn.microsoft.com/ru-ru/dotnet/api/microsoft.sharepoint.client.fielduservalue.email?view=sharepoint-csom

Does anyone know what might have changed or why this has stopped working?