fix(Cascader): refine selection logic for leaf node in single mode (#3840)

Author: RylanBot

packages/components/cascader/core/className.ts

@@ -41,7 +41,10 @@ export function getNodeStatusClass(
 
  const isDisabled = node.disabled || (multiple && (value as TreeNodeValue[]).length >= max && max !== 0);
 
- const isSelected = node.checked || (multiple && !checkStrictly && node.expanded && !isLeaf);
+ let isSelected = node.checked || (multiple && !checkStrictly && node.expanded && !isLeaf);
+ if (!multiple && !checkStrictly && !isLeaf) {
+ isSelected = node.expanded;
+ }
 
  return [
  {