The blog preview not showing when embedding WordPress blog links

[galakhyati]

Steps to Reproduce

1. On the page editor, paste the link to a post. URL: https://vietnamhoonist.com/2021/08/31/tong-hop-tin-tuc-thang-8-2021/ It doesn't unfurl, but only shows a link that is embedded without any preview on the editor.
2. When previewing the page, it doesn't show the preview of the post shared, it only shows a link.
3. Shared another link from the same site on the editor, it unfurls and shows the preview.
4. When previewing the page on the front end, it doesn't show the preview on the front end.
5. Checked by pasting link from another blog (simple as well as an atomic site), it unfurls in the editor as well as on the front end.

Screen.Capture.on.2021-08-31.at.12-08-00.mp4

What I expected to happen

When any link is pasted on the editor, it should unfurl and show on the front end.

What actually happened

Some links from the site unfurl on the editor but never on the front end.

Context

Customer report

Operating System

Windows, macOS

OS Version

No response

Browser

Chrome/Chromium

Browser Version(s)

No response

Is this specific to applied theme? If so, what is the theme name?

No response

Simple/Atomic

Simple

Console and/or error logs

No errors in the console

Number of Users Impacted

One user

Available Workarounds

No response

Reproducibility

Consistent

Other information

I'm able to replicate the issue when sharing the links from the user's site.
Slack: p1630417859035100-slack-C7YPUHBB2 & p1630391925482000-slack-C03TY6J1A
Chat: 31410986-hc
Follow up ticket: 4261160-zen
User's site: http://vietnamhoonist.wordpress.com
Test post where I checked: p95aOX-yD-p2

[kosiew]

Hi @galakhyati ,

Thanks for reporting this and the detailed steps.

WordPress/gutenberg#32689 says that internal links should show preview too.

[kosiew]

As I could also reproduce on a Jurassic Ninja site, I filed a Gutenberg issue - WordPress/gutenberg#34676

Closing this in favour to WordPress/gutenberg#34676

[jordesign]

Closing in favour of #56279