I believe this is a bug in how html in email automations are processed:
If I try to send an email using `[markdown](...)` syntax with a inserted URL from a record it works fine, but if I try to do the same with `<a href="...">example</a> then it seems that markdown processing is applied to the inserted URL; in this case the inserted URL includes _underscores_, and extra `<i>` tags are inserted in the link.