The cause is not WP, but the coding of the pages. In this page
https://fotografodimatrimoni.fabiothian.com/
the link text is enclosed in a span tag that sets the color:
<a target="_blank" href="https://www.fabiothian.com/weddings">
<span style="color: #808080;">
<strong>> Visitate il mio portfolio <</strong>
</span>
</a>
In this page:
https://fotografodimatrimonio.fabiothian.com/http:/
the span encloses the entire link, not just the text, so the behaviour is different:
<span style="color: #606060;">
<strong>
<a target="_blank" href="https://www.fabiothian.com/weddings">> Visitate la mia galleria <</a>
</strong>
</span>
You have coded the entries differently on the two pages.