HarmonyOS Web组件grayscale属性设置未能生效

import web_webview from '@ohos.web.webview'

@Entry
@Component
struct WebComponent {
  controller: web_webview.WebviewController = new web_webview.WebviewController()

  build() {
    Column() {
      Web({ src: 'www.huawei.com', controller: this.controller })
        .grayscale(0.5)
    }
  }
}