I found the problem: is in articles navigation, if I deactivate that articles option no error are shown.
If article navigation is active it generate "forward" and "backward" buttons like this:
<ul class="pager pagenav">
<li class="next">
<a class="hasTooltip" title="..." aria-label="..." href="/..." rel="next">
<span aria-hidden="true">Avanti</span> <span class="icon-chevron-right" aria-hidden="true"></span> </a>
</li>
</ul>
So the "hasTooltip" class generate error if use bootstrap5.
I don't know if I can fix this and can reactivate that articles option.