Ticket #51522: 51522-site-icon.css.patch

src/wp-admin/css/site-icon.css

@@ -51 +51 @@
 
 .customize-control-site_icon .app-icon-preview {
         margin-top: 9px;
+        display: inline-block;
+        padding: 3px;
+        color: #fff;
 }