--- a/toolkit/mozapps/extensions/content/extensions.xml
+++ b/toolkit/mozapps/extensions/content/extensions.xml
@@ -898,17 +898,17 @@
           this.setAttribute("previewURL", previewURL ? previewURL : "");
           this.setAttribute("hasPreview", previewURL ? "true" : "fase");
 
           let legacyWarning = legacyExtensionsEnabled && !this.mAddon.install &&
             isLegacyExtension(this.mAddon);
           this.setAttribute("legacy", legacyWarning);
           document.getAnonymousElementByAttribute(this, "anonid", "legacy").href = SUPPORT_URL + "webextensions";
 
-          if (!allowPrivateBrowsingByDefault) {
+          if (!allowPrivateBrowsingByDefault && this.mAddon.type === "extension") {
             ExtensionPermissions.get(this.mAddon.id).then((perms) => {
               let allowed = perms.permissions.includes("internal:privateBrowsingAllowed");
               this.setAttribute("privateBrowsing", allowed);
               if (!allowed && PrivateBrowsingUtils.isContentWindowPrivate(window)) {
                 // Hide the preferences button if the current window is
                 // private and the addon is not allowed to access it.
                 this._preferencesBtn.hidden = true;
               }

--- a/toolkit/mozapps/extensions/test/browser/browser_theme_previews.js
+++ b/toolkit/mozapps/extensions/test/browser/browser_theme_previews.js
@@ -130,13 +130,19 @@ add_task(async function testThemeOrderin
     idOrder,
     [
       themeId(8), // The active theme first.
       themeId(6), themeId(7), // With previews, ordered by name.
       themeId(5), // The theme without a preview last.
     ],
     "Themes are ordered by enabled, previews, then name");
 
+  // Ensure allow in private mode badge is hidden for themes.
+  for (let item of list.itemChildren) {
+    let badge = gManagerWindow.document.getAnonymousElementByAttribute(item, "anonid", "privateBrowsing");
+    is_element_hidden(badge, `private browsing badge is hidden`);
+  }
+
   await close_manager(gManagerWindow);
   for (let addon of await promiseAddonsByIDs(themeIds)) {
     await addon.uninstall();
   }
 });