https://dojo.telerik.com/ORahihiZ/2
The second editor (NumericTextBox) in the popup is focused by default.
Since the form's focusFirst option is enabled, the first editor (textarea) in the popup should be focused by default.
As a workaround, the textarea can be focused in the editCard event handler:
function onEditCard(e) {
setTimeout(function() {
$(".k-taskboard-pane-content textarea").focus();
}, 100)
}