Issues with website since PHP 8.0

Hi, our hosting provider upgraded all websites to PHP 8.0. Since then, we have been experiencing issues with our Unicon websites.
It seems like all our websites using theme Unicon are giving us issues.
Our main website of concern is giving us an error when trying to edit a page, whether we edit it with WPBakery or Elementor we get the “your website is experiencing a critical error” warning.
As mentioned our other websites that do not use theme Unicon do not give us these issues only our Unicon sites.
We have Unicon 2.9.1 installed.
Please help as our hosting provider will only support PHP 7.4 until December this year so we need to resolve the issues before then.

Ticket