Catch box theme php compatibility

Hello, I have a website with this theme Catch Box. My hosting service asked to update the php version from 7.4 to 8.1. But when I try to update the php version, the website is no longer accessible. There is a message which says that a critical error has occured (Google Chrome) and images are not appearing on other browsers. My plugins and Wordpress are already updated. Can you, please, tell me how I can update to php 8.1 without having this error? My website is https://permessodisoggiorno.org/ Thank you very much! Gama