What determines whether a link will generate a preview or stay a link?

[jayhawku]

My forum relies on sharing news and often links to news sites that sometimes generates a preview of the story:

Lloyd Austin leaving -Redacted- in dark over hospitalization raises questions​

The president and several other senior government officials were unaware that the secretary of defense had been admitted to hospital.

www.newsweek.com

But often, it won't generate a preview like below:

https://www.cnn.com/2024/01/08/politics/-Redacted--courtroom-campaign-iowa/index.html

What determines if a preview will generate? I thought perhaps it was a paywall but it's not that.

Thanks!
What determines whether a link will generate a preview or stay a link?

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