HarmonyOS 有出现动画，但没有消失动画

@Entry
@Component
struct Index {
  @State message: string = 'Hello World';
  @State flag: boolean = true
  build() {
    Stack() {
      if (this.flag) {
        Column() {
          Text(this.message)
            .id('HelloWorld')
            .fontColor(Color.Red)
            .fontSize(50)
            .fontWeight(FontWeight.Bold)
            .transition(TransitionEffect.translate({ y: 100 }).animation({ duration: 500 }))
        }
        // .transition(TransitionEffect.scale({ x: 0.5,y: 0.5 }).animation({ duration: 500 }))
      }
      Button('控制一下')
        .width(100)
        .height(100)
        .onClick(() => {
          this.flag = !this.flag
        })
    }
    .height('100%')
    .width('100%')
  }
}