Fix download hashtags

Closes #2144.

docs/basic-usage.rst

@@ -99,7 +99,7 @@ Instaloader supports the following targets:
       to **download IGTV videos**.
 
 - ``"#hashtag"``
-   Posts with a certain **hashtag** (the quotes are usually necessary).
+   Posts with a certain **hashtag** (the quotes are usually necessary). Requires :ref:`login<login>`.
 
 - ``%location id``
    Posts tagged with a given location; the location ID is the numerical ID

instaloader/instaloader.py

@@ -1215,6 +1215,7 @@ class Instaloader:
            Use :meth:`Hashtag.get_posts_resumable`."""
         return Hashtag.from_name(self.context, hashtag).get_posts_resumable()
 
+    @_requires_login
     def download_hashtag(self, hashtag: Union[Hashtag, str],
                          max_count: Optional[int] = None,
                          post_filter: Optional[Callable[[Post], bool]] = None,

instaloader/structures.py

@@ -1862,7 +1862,9 @@ class Hashtag:
         return self._node["name"].lower()
 
     def _query(self, params):
-        json_response = self._context.get_json("explore/tags/{0}/".format(self.name), params)
+        json_response = self._context.get_iphone_json(
+            "api/v1/tags/web_info/", {**params, "tag_name": self.name}
+        )
         return json_response["graphql"]["hashtag"] if "graphql" in json_response else json_response["data"]
 
     def _obtain_metadata(self):