解决“Angular SSR 9中的‘twice loading image and flickering site’问题”可以使用以下代码示例：

在Angular SSR 9中，可以使用ngx-universal-injector库来解决这个问题。该库可以在服务器端和客户端之间共享状态，以便避免重复加载图片和闪烁网站。

首先，安装ngx-universal-injector库：

npm install ngx-universal-injector

然后，在你的Angular项目中创建一个服务，例如shared-state.service.ts：

import { Injectable } from '@angular/core';
import { UniversalInjector } from 'ngx-universal-injector';

@Injectable({
  providedIn: 'root'
})
export class SharedStateService {
  private sharedState: any = {};

  constructor(private universalInjector: UniversalInjector) {
    this.sharedState = this.universalInjector.get('sharedState') || {};
    this.universalInjector.set('sharedState', this.sharedState);
  }

  public getSharedState(): any {
    return this.sharedState;
  }
}

接下来，在你的组件中使用SharedStateService来共享图片加载状态：

import { Component, OnInit } from '@angular/core';
import { SharedStateService } from './shared-state.service';

@Component({
  selector: 'app-example',
  template: `
    
  `
})
export class ExampleComponent implements OnInit {
  isLoading: boolean;
  isLoaded: boolean;

  constructor(private sharedStateService: SharedStateService) {}

  ngOnInit() {
    const sharedState = this.sharedStateService.getSharedState();
    this.isLoading = sharedState.isLoading || false;
    this.isLoaded = sharedState.isLoaded || false;
  }

  onImageLoad() {
    this.isLoading = false;
    this.isLoaded = true;

    const sharedState = this.sharedStateService.getSharedState();
    sharedState.isLoading = this.isLoading;
    sharedState.isLoaded = this.isLoaded;
  }
}

最后，在服务器端的main.server.ts文件中，使用ngx-universal-injector来共享图片加载状态：

import { enableProdMode } from '@angular/core';
import { renderModuleFactory } from '@angular/platform-server';
import { provideModuleMap } from '@nguniversal/module-map-ngfactory-loader';
import { createServerRenderer, RenderResult } from 'ngx-universal-injector';
import * as fs from 'fs';
import * as path from 'path';

const { AppServerModuleNgFactory, LAZY_MODULE_MAP } = require('./dist/server/main');

enableProdMode();

const indexHtml = fs.readFileSync(path.resolve(__dirname, './dist/browser/index.html'), 'utf-8');

const render = createServerRenderer((params: any): RenderResult => {
  const { AppServerModule, LAZY_MODULE_MAP } = params;
  const { AppServerModuleNgFactory, LAZY_MODULE_MAP } = require('./dist/server/main');
  const moduleFactory = AppServerModuleNgFactory || AppServerModule;
  const moduleRef = moduleFactory.create(appInjector);

  return {
    moduleRef,
    async render(document: any) {
      const html = await renderModuleFactory(moduleFactory, {
        document: indexHtml,
        url: params.url,
        extraProviders: [provideModuleMap(LAZY_MODULE_MAP)]
      });

      return {
        html
      };
    }
  };
});

export default render;

通过以上步骤，你可以在Angular SSR 9中解决“twice loading image and flickering site”的问题，实现“两次加载图片和闪烁的网站”的解决方案。