I keep losing links when I switch to visual editor in WordPress

I have this problem in a specific page of my wordpress website (using the classic editor): when I switch from text editor to visual editor I immediately lose all my links (placed in a div element).

I give you a detailed example of what happen every time:

<strong>I start editing my page and the section with href looks like this:</strong>

<section class="cards-wrapper">
<div class="card-grid-space">
<div class="card">
<div>
<h1>Test di Primo Orientamento</h1>
Un semplice e divertente test di 10 minuti con risultato immediato per avere qualche idea iniziale su quale facoltà potrebbe essere giusta per te.
<div class="tags">
<a href="https://www.universitaeuropeadiroma.it/test/"><div class="tag">VAI AL TEST</div></a>
&nbsp;

</div>
</div>
</div>
</div>

<strong>Then, if I switch to visual editor and come back to the text, it becomes like this</strong>

<section class="cards-wrapper">
<div class="card-grid-space">
<div class="card">
<div>
<h1>Test di Primo Orientamento</h1>
Un semplice e divertente test di 10 minuti con risultato immediato per avere qualche idea iniziale su quale facoltà potrebbe essere giusta per te.
<div class="tags">
<div class="tag">VAI AL TEST</div>
&nbsp;

</div>
</div>
</div>
</div>

As you can see the “a” element has disappeared and it’s very annoying because I have to replace all my links every time or switch to a previous edit and losing my recent ones.

How can i solve this? I would like to be able to switch freely between text and visual editors without losing any code.

Thanks a lot.