diff -u b/core/includes/theme.inc b/core/includes/theme.inc
--- b/core/includes/theme.inc
+++ b/core/includes/theme.inc
@@ -2046,14 +2046,14 @@
       'variables' => ['url' => NULL, 'title' => NULL],
     ],
     'progress_bar' => [
-      'variables' => ['label' => NULL, 'percent' => NULL, 'message' => NULL, 'animate' => TRUE],
+      'variables' => ['label' => NULL, 'percent' => NULL, 'message' => NULL],
     ],
     'indentation' => [
       'variables' => ['size' => 1],
       'variables' => ['url' => NULL, 'title' => NULL],
     ],
     'progress_bar' => [
-      'variables' => ['label' => NULL, 'percent' => NULL, 'message' => NULL],
+      'variables' => ['label' => NULL, 'percent' => NULL, 'message' => NULL, 'animate' => TRUE],
     ],
     'indentation' => [
       'variables' => ['size' => 1],
diff -u b/core/tests/Drupal/KernelTests/Core/Theme/ConfirmClassyCopiesTest.php b/core/tests/Drupal/KernelTests/Core/Theme/ConfirmClassyCopiesTest.php
--- b/core/tests/Drupal/KernelTests/Core/Theme/ConfirmClassyCopiesTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Theme/ConfirmClassyCopiesTest.php
@@ -702,7 +702,7 @@
         'more-link.css' => 'b2ebfb826e035334340193b42246b180',
         'node.css' => '81ea0a3fef211dbc32549ac7f39ec646',
         'pager.css' => 'd10589366720f9c15b66df434baab4da',
-        'progress.css' => '330816d5590e249e3c94d5ff0b8927e8',
+        'progress.css' => 'f506476ac50048d7743603fa17241e14',
         'search-results.css' => 'ce3ca8fcd54e72f142ba29da5a3a5c9a',
         'tabledrag.css' => '98d24ff864c7699dfa6da9190c5e70df',
         'tableselect.css' => '8e966ac85a0cc60f470717410640c8fe',