diff --git a/app/assets/javascripts/discourse/components/iframed-html.js.es6 b/app/assets/javascripts/discourse/components/iframed-html.js.es6
deleted file mode 100644
index f05b5d278b8..00000000000
--- a/app/assets/javascripts/discourse/components/iframed-html.js.es6
+++ /dev/null
@@ -1,18 +0,0 @@
-import Component from "@ember/component";
-
-export default Component.extend({
-  tagName: "iframe",
-  html: null,
-  className: "",
-  classNameBindings: ["html:iframed-html", "className"],
-  sandbox: "allow-same-origin",
-  attributeBindings: ["sandbox:sandbox"],
-
-  didRender() {
-    this._super(...arguments);
-    const iframeDoc = this.element.contentWindow.document;
-    iframeDoc.open("text/html", "replace");
-    iframeDoc.write(this.html);
-    iframeDoc.close();
-  }
-});
diff --git a/app/controllers/uploads_controller.rb b/app/controllers/uploads_controller.rb
index 2c64cbed0e7..64fcd795b58 100644
--- a/app/controllers/uploads_controller.rb
+++ b/app/controllers/uploads_controller.rb
@@ -162,12 +162,6 @@ class UploadsController < ApplicationController
       return redirect_to Discourse.store.url_for(upload)
     end
 
-    # url_for figures out the full URL, handling multisite DBs,
-    # and will return a presigned URL for the upload
-    if path_with_ext.blank?
-      return redirect_to Discourse.store.url_for(upload)
-    end
-
     redirect_to Discourse.store.signed_url_for_path(path_with_ext)
   end
 
diff --git a/app/models/topic_list.rb b/app/models/topic_list.rb
index d51c0f153f3..52b0ee00708 100644
--- a/app/models/topic_list.rb
+++ b/app/models/topic_list.rb
@@ -67,7 +67,7 @@ class TopicList
 
   def preload_key
     if @category
-      "topic_list_#{@category.url.sub(/^\//, '')}/#{@category.id}/l/#{@filter}"
+      "topic_list_#{@category.url.sub(/^\//, '')}/l/#{@filter}"
     else
       "topic_list_#{@filter}"
     end
diff --git a/lib/topic_query.rb b/lib/topic_query.rb
index cbfa2ed999b..5f8658661b4 100644
--- a/lib/topic_query.rb
+++ b/lib/topic_query.rb
@@ -1059,29 +1059,6 @@ class TopicQuery
 
   private
 
-  def subcategory_ids(category_id)
-    @subcategory_ids ||= {}
-    @subcategory_ids[category_id] ||=
-      begin
-        sql = <<~SQL
-            WITH RECURSIVE subcategories AS (
-                SELECT :category_id id, 1 depth
-                UNION
-                SELECT categories.id, (subcategories.depth + 1) depth
-                FROM categories
-                JOIN subcategories ON subcategories.id = categories.parent_category_id
-                WHERE subcategories.depth < :max_category_nesting
-            )
-            SELECT id FROM subcategories
-          SQL
-        DB.query_single(
-          sql,
-          category_id: category_id,
-          max_category_nesting: SiteSetting.max_category_nesting
-        )
-      end
-  end
-
   def sanitize_sql_array(input)
     ActiveRecord::Base.public_send(:sanitize_sql_array, input.join(','))
   end
diff --git a/spec/requests/uploads_controller_spec.rb b/spec/requests/uploads_controller_spec.rb
index 7f37c75e16e..0be31c1811f 100644
--- a/spec/requests/uploads_controller_spec.rb
+++ b/spec/requests/uploads_controller_spec.rb
@@ -417,17 +417,6 @@ describe UploadsController do
           get upload.short_path
           expect(response.code).to eq("403")
         end
-
-        context "when running on a multisite connection" do
-          before do
-            Rails.configuration.multisite = true
-          end
-          it "redirects to the signed_url_for_path with the multisite DB name in the url" do
-            freeze_time
-            get upload.short_path
-            expect(response.body).to include(RailsMultisite::ConnectionManagement.current_db)
-          end
-        end
       end
     end
   end
diff --git a/test/javascripts/components/iframed-html-test.js.es6 b/test/javascripts/components/iframed-html-test.js.es6
deleted file mode 100644
index ad7d4113f49..00000000000
--- a/test/javascripts/components/iframed-html-test.js.es6
+++ /dev/null
@@ -1,23 +0,0 @@
-import componentTest from "helpers/component-test";
-
-moduleForComponent("iframed-html", { integration: true });
-
-componentTest("appends the html into the iframe", {
-  template: `{{iframed-html html="<h1 id='find-me'>hello</h1>" className='this-is-an-iframe'}}`,
-
-  async test(assert) {
-    const iframe = find("iframe.this-is-an-iframe");
-    assert.equal(iframe.length, 1, "inserts an iframe");
-
-    assert.ok(
-      iframe[0].classList.contains("this-is-an-iframe"),
-      "Adds className to the iframes classList"
-    );
-
-    assert.equal(
-      iframe[0].contentWindow.document.body.querySelectorAll("#find-me").length,
-      1,
-      "inserts the passed in html into the iframe"
-    );
-  }
-});