For a website with domain name "foo.tld", the external URL "foo.tld.countrycode" is not recognized as external.
As real example, while working on childcare.gov, content editors noted that links to the external site https://www.childcare.gov.mp (with the country code TLD) were not recognized as external.
The regex pattern in extlinks.js needs adjustment to discern this better. (I'd propose a patch, but my regex skills aren't up to the task.)
I was able to workaround the issue by adding a matching pattern (childcare.gov\.[a-z]{2,3}) on the configuration form, so the links on the page noted above do now show up as external.
Tweak the regex expression in extlinks.js. (I do understand if this is an edge case and is marked as "will not fix," especially since there is a workaround.)
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Closed: cannot reproduce
2.0
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So just tested using the link https://www.childcare.gov.mp/ and the icon gets placed just fine. Is there something missing?