diff --git a/app/assets/javascripts/admin/addon/components/modal/site-setting-default-categories.hbs b/app/assets/javascripts/admin/addon/components/modal/site-setting-default-categories.hbs
new file mode 100644
index 00000000000..d83e9b0e449
--- /dev/null
+++ b/app/assets/javascripts/admin/addon/components/modal/site-setting-default-categories.hbs
@@ -0,0 +1,23 @@
+<DModal
+  class="incoming-emails"
+  @title={{html-safe @model.siteSetting.key}}
+  @closeModal={{this.cancel}}
+>
+  <:body>
+    {{i18n
+      "admin.site_settings.default_categories.modal_description"
+      count=@model.siteSetting.count
+    }}
+  </:body>
+  <:footer>
+    <DButton
+      @action={{this.updateExistingUsers}}
+      class="btn-primary"
+      @label="admin.site_settings.default_categories.modal_yes"
+    />
+    <DButton
+      @action={{this.cancel}}
+      @label="admin.site_settings.default_categories.modal_no"
+    />
+  </:footer>
+</DModal>
\ No newline at end of file
diff --git a/app/assets/javascripts/admin/addon/components/modal/site-setting-default-categories.js b/app/assets/javascripts/admin/addon/components/modal/site-setting-default-categories.js
new file mode 100644
index 00000000000..88539f620fb
--- /dev/null
+++ b/app/assets/javascripts/admin/addon/components/modal/site-setting-default-categories.js
@@ -0,0 +1,16 @@
+import Component from "@glimmer/component";
+import { action } from "@ember/object";
+
+export default class SiteSettingDefaultCategories extends Component {
+  @action
+  updateExistingUsers() {
+    this.args.model.setUpdateExistingUsers(true);
+    this.args.closeModal();
+  }
+
+  @action
+  cancel() {
+    this.args.model.setUpdateExistingUsers(false);
+    this.args.closeModal();
+  }
+}
diff --git a/app/assets/javascripts/admin/addon/controllers/modals/site-setting-default-categories.js b/app/assets/javascripts/admin/addon/controllers/modals/site-setting-default-categories.js
deleted file mode 100644
index e7e970578bd..00000000000
--- a/app/assets/javascripts/admin/addon/controllers/modals/site-setting-default-categories.js
+++ /dev/null
@@ -1,8 +0,0 @@
-import Controller from "@ember/controller";
-import ModalFunctionality from "discourse/mixins/modal-functionality";
-import ModalUpdateExistingUsers from "discourse/mixins/modal-update-existing-users";
-
-export default class SiteSettingDefaultCategoriesController extends Controller.extend(
-  ModalFunctionality,
-  ModalUpdateExistingUsers
-) {}
diff --git a/app/assets/javascripts/admin/addon/mixins/setting-component.js b/app/assets/javascripts/admin/addon/mixins/setting-component.js
index f560e36eeb9..455991badf0 100644
--- a/app/assets/javascripts/admin/addon/mixins/setting-component.js
+++ b/app/assets/javascripts/admin/addon/mixins/setting-component.js
@@ -7,10 +7,11 @@ import { ajax } from "discourse/lib/ajax";
 import { categoryLinkHTML } from "discourse/helpers/category-link";
 import discourseComputed, { bind } from "discourse-common/utils/decorators";
 import { htmlSafe } from "@ember/template";
-import showModal from "discourse/lib/show-modal";
 import { warn } from "@ember/debug";
 import { action } from "@ember/object";
 import { splitString } from "discourse/lib/utilities";
+import { inject as service } from "@ember/service";
+import SiteSettingDefaultCategoriesModal from "../components/modal/site-setting-default-categories";
 
 const CUSTOM_TYPES = [
   "bool",
@@ -74,6 +75,8 @@ const DEFAULT_USER_PREFERENCES = [
 ];
 
 export default Mixin.create({
+  modal: service(),
+  site: service(),
   attributeBindings: ["setting.setting:data-setting"],
   classNameBindings: [":row", ":setting", "overridden", "typeClass"],
   validationMessage: null,
@@ -190,22 +193,24 @@ export default Mixin.create({
     });
 
     const count = result.user_count;
-
     if (count > 0) {
-      const controller = showModal("site-setting-default-categories", {
-        model: { count, key: key.replaceAll("_", " ") },
-        admin: true,
-      });
-
-      controller.set("onClose", () => {
-        this.updateExistingUsers = controller.updateExistingUsers;
-        this.save();
+      await this.modal.show(SiteSettingDefaultCategoriesModal, {
+        model: {
+          siteSetting: { count, key: key.replaceAll("_", " ") },
+          setUpdateExistingUsers: this.setUpdateExistingUsers,
+        },
       });
+      this.save();
     } else {
       await this.save();
     }
   },
 
+  @action
+  setUpdateExistingUsers(value) {
+    this.updateExistingUsers = value;
+  },
+
   @action
   async save() {
     try {
diff --git a/app/assets/javascripts/admin/addon/templates/modal/site-setting-default-categories.hbs b/app/assets/javascripts/admin/addon/templates/modal/site-setting-default-categories.hbs
deleted file mode 100644
index 53a486173af..00000000000
--- a/app/assets/javascripts/admin/addon/templates/modal/site-setting-default-categories.hbs
+++ /dev/null
@@ -1,18 +0,0 @@
-<DModalBody @class="incoming-emails" @rawTitle={{this.model.key}}>
-  {{i18n
-    "admin.site_settings.default_categories.modal_description"
-    count=this.model.count
-  }}
-</DModalBody>
-
-<div class="modal-footer">
-  <DButton
-    @action={{action "updateExistingUsers"}}
-    @class="btn-primary"
-    @label="admin.site_settings.default_categories.modal_yes"
-  />
-  <DButton
-    @action={{action "cancel"}}
-    @label="admin.site_settings.default_categories.modal_no"
-  />
-</div>
\ No newline at end of file
diff --git a/app/assets/javascripts/discourse/app/mixins/modal-update-existing-users.js b/app/assets/javascripts/discourse/app/mixins/modal-update-existing-users.js
deleted file mode 100644
index 699061545f5..00000000000
--- a/app/assets/javascripts/discourse/app/mixins/modal-update-existing-users.js
+++ /dev/null
@@ -1,19 +0,0 @@
-import Mixin from "@ember/object/mixin";
-
-export default Mixin.create({
-  onShow() {
-    this.set("updateExistingUsers", null);
-  },
-
-  actions: {
-    updateExistingUsers() {
-      this.set("updateExistingUsers", true);
-      this.send("closeModal");
-    },
-
-    cancel() {
-      this.set("updateExistingUsers", false);
-      this.send("closeModal");
-    },
-  },
-});
diff --git a/app/assets/javascripts/discourse/app/services/modal.js b/app/assets/javascripts/discourse/app/services/modal.js
index 683e63a0cfc..396192afe40 100644
--- a/app/assets/javascripts/discourse/app/services/modal.js
+++ b/app/assets/javascripts/discourse/app/services/modal.js
@@ -48,7 +48,6 @@ const KNOWN_LEGACY_MODALS = [
   "topic-summary",
   "user-status",
   "admin-penalize-user",
-  "site-setting-default-categories",
   "admin-badge-preview",
   "admin-edit-badge-groupings",
   "admin-reseed",