XML sitemap generated has invalid format if we check it against sitemap XSD.
To check it you can use this XML Validation tool. In demoauthor.magnolia-cms.com, create a sitemap for travel site and validate xml content (due to MGNLGS-119 url cannot be validated) against sitemap current XSD.
Result for each url:
This is believed to be resulting in a number of pages not being correctly indexed by Google. More information in ticket: SUPPORT-6137