Problem with WebP and Thumb

I’m on CloudFlare so I use the Alt webp. Images on posts works fine but the thumb on related content are broken. Why?

This is the (broken) code generated:

<li>
<a class="rh_related_link_image" href="https://www.xiaomitoday.it/uc-browser-e-countdown-allo-xiaomi-mi-6.html">
<figure>
<img class="lazyimages" data-src="https://www.xiaomitoday.it/wp-content/uploads/thumbs_dir/mi-6-countdown2-n6l0umbu2ejkk09a394f8x17dgm18gej7svrxkuxoq.png" alt="UC browser e il countdown allo Xiaomi Mi 6" src="https://www.xiaomitoday.it/wp-content/uploads/thumbs_dir/mi-6-countdown2-n6l0umbu2ejkk09a394f8x17dgm18gej7svrxkuxoq.png" style="opacity: 1;" height="130">
</figure>
class="rh_table_image">
</a>
<a class="rh_related_link" href="https://www.xiaomitoday.it/uc-browser-e-countdown-allo-xiaomi-mi-6.html" rel="bookmark" title="UC browser e il countdown allo Xiaomi Mi 6">UC browser e il countdown allo Xiaomi Mi 6</a>
</li>