Changing the output - Headline block

Good morning everyone and happy new year

Some time ago I had a plugin created/edited to handle events, necessary for the creation of a work in progress site.
Everything has always worked fine.
After about a month, I've started again the site and I noticed this "hitch" that I think is due to the theme.
As a matter of fact, some characters are changed and this prevents the correct output.
Practically:
- I insert a short-code that should publish a link category, but in fact this is converted into a text string.
I tried to put it in different areas but I get the same result.
generated short-code

if ( ($page_cats_hide != 'yes') ) {
		$cats_raw = wp_strip_all_tags( get_the_term_list( get_the_ID(), 'event_cat', '<span>', ' '.$cat_separator.' ', '</span>' ) );
		$cats = get_the_term_list( get_the_ID(), 'event_cat', '<span>', ' '.$cat_separator.' ', '</span>' );

di fatto viene pubblicato in questo modo
<span><a href=&quot;https://siteweb/corsi-eventi-categorie/leadership/&quot; rel=&quot;tag&quot;>Leadership</a> | <a href=&quot;https://siteweb/corsi-eventi-categorie/mbraining/&quot; rel=&quot;tag&quot;>mBraining</a></span>

it seems that instead of the < character the code ascii &gt is put;

I don't understand what is the reason
Thanks for the support