diff --git a/src/docs/src/UI/showFeedbackDialog.md b/src/docs/src/UI/showFeedbackDialog.md
index ea9ca094d..e1bdcc772 100644
--- a/src/docs/src/UI/showFeedbackDialog.md
+++ b/src/docs/src/UI/showFeedbackDialog.md
@@ -27,6 +27,8 @@ None.
 ## Return value
 A `Promise` that resolves to `true` if the user submitted feedback, and `false` if the dialog was dismissed or feedback is unavailable. It never rejects.
 
+On a website that is cross-origin isolated (COOP severs the popup's connection to your page), the promise resolves `false` even though the popup stays open and the user may still submit their feedback there. Treat `false` as "not confirmed", not "not sent".
+
 ## Examples
 
 ```html;ui-show-feedback-dialog
diff --git a/src/puter-js/src/modules/UI.js b/src/puter-js/src/modules/UI.js
index 14b327b78..4deae7995 100644
--- a/src/puter-js/src/modules/UI.js
+++ b/src/puter-js/src/modules/UI.js
@@ -1684,7 +1684,10 @@ class UI extends EventListener {
      *
      * @returns {Promise<boolean>} `true` when the user submitted feedback,
      *   `false` when the dialog was dismissed or feedback is unavailable.
-     *   Never rejects.
+     *   Never rejects. On a cross-origin-isolated page COOP severs the
+     *   popup's link to the opener, so the promise resolves `false` while
+     *   the popup stays open and the user may still submit — `false` means
+     *   "not confirmed", not "not sent".
      */
     async showFeedbackDialog () {
         if ( this.env === 'app' ) {