Image Compare Block: full image URLs are saved in post content, with CDN URL if used

[jeherve]

Impacted plugin

Jetpack

Quick summary

When using the Image Compare Block, the full image URL is saved in the post content. It's problematic when using an image CDN like Photon. If that CDN is then deactivated or its URL changes, the images in the post content will continue to use the old CDN URL

Steps to reproduce

1. Start with a site using the Jetpack plugin, connected to WordPress.com.
2. Go to Jetpack > Settings > Performance, and activate the Site Accelerator feature.
3. Go to Posts > Add New
4. Add an Image Compare Block
5. Upload 2 images, and publish your post.
6. Visit the post on the frontend, and open your browser's dev tools.
7. The images use the CDN URL.
8. Edit the post, and switch to the code editor view.
9. You'll see that the images stored in the post content are the full image URLs, with the i0.wp.com prefix.
10. Now go to Jetpack > Settings > Performance again, and deactivate the Site Accelerator feature.
11. Go back to the post.

A clear and concise description of what you expected to happen.

I would expect the post to not use the CDN URL anymore.

What actually happened

Instead, it still uses the image CDN since the full image was stored in the post content.

Impact

Some (< 50%)

Available workarounds?

No but the platform is still usable

If the above answer is "Yes...", outline the workaround.

No response

Platform (Simple and/or Atomic)

Atomic, Self-hosted

Logs or notes

Reported here:
https://wordpress.org/support/topic/bug-in-image-compare-block/

[github-actions]

This issue has been marked as stale. This happened because:

• It has been inactive for the past 6 months.
• It hasn’t been labeled `[Pri] BLOCKER`, `[Pri] High`, `[Type] Feature Request`, `[Type] Enhancement`, `[Type] Janitorial`, `Good For Community`, `[Type] Good First Bug`, etc.

No further action is needed. But it's worth checking if this ticket has clear reproduction steps and it is still reproducible. Feel free to close this issue if you think it's not valid anymore — if you do, please add a brief explanation.