Media:thumbnail – Error reading SmartFormat XML content

Hi!

I’ve installed and configured my staging site with the plugin, but when I go to the SmartNews Feed Validator, I see an error:

Error reading SmartFormat XML content. Details: Failed to parse XML at line 22 column 77. - Excerpt near invalid part: '...://domainxxx.imgix.net/2023/01/z1.jpg?fm=pjpg&ixlib=php-3.3.0&s=92f21b43fea78c223b92bfa5dbd4d3f1</med...' - Cause: The reference to entity "ixlib" must end with the ';' delimiter.

I believe the media:thumbnail is using a wrong sintaxe. How it is:

<media:thumbnail>https://domainxxx.imgix.net/2023/01/z1.jpg?fm=pjpg&ixlib=php-3.3.0&s=92f21b43fea78c223b92bfa5dbd4d3f1</media:thumbnail&gt;

How it should be as per the link https://publishers.smartnews.com/hc/en-us/articles/360036526213-SmartFormat-Specification-Version-2-1- :

<media:thumbnail url="https://domainxxx.imgix.net/2023/01/z1.jpg?fm=pjpg&ixlib=php-3.3.0&s=92f21b43fea78c223b92bfa5dbd4d3f1" />

Thank you in advance!