[Bug]: Full-page screenshot doesn't render iframe content

Version

1.59.1

Steps to reproduce

1. Clone my repo at https://github.com/afonseca08/playwright-render-issue
2. npm ci
3. npx playwright install chromium
4. npm run repro
5. See screenshots under test-results/youtube-fullpage-iframe-*/

Expected behavior

full-page.png should show the same loaded YouTube player content that appears in viewport-after-scroll.png and iframe-element.png.

Actual behavior

full-page.png captures the YouTube iframe rectangle as blank white.

Additional context

See screenshots:

Full screen capture

Viewport after scroll capture

Environment

System:
    OS: Linux 6.6 Ubuntu 24.04.4 LTS 24.04.4 LTS (Noble Numbat)
    CPU: (12) x64 AMD Ryzen 5 5600X 6-Core Processor
    Memory: 14.43 GB / 15.58 GB
    Container: Yes
  Binaries:
    Node: 18.19.1 - /usr/bin/node
    npm: 9.2.0 - /usr/bin/npm
  IDEs:
    VSCode: 1.118.1 - /mnt/c/Users/Alberto/AppData/Local/Programs/Microsoft VS Code/bin/code
  Languages:
    Bash: 5.2.21 - /usr/bin/bash
  npmPackages:
    @playwright/test: ^1.59.1 => 1.59.1

Start with the linked reproduction repository: run npm ci, npx playwright install chromium, and npm run repro. Compare full-page.png with viewport-after-scroll.png and iframe-element.png under test-results; done means the full-page screenshot includes the loaded YouTube iframe content rather than a blank white rectangle.