How do I fix this fatal error?

I've reached out to Divi support but response times are painful so hoping for some guidance here in the meantime.

I completed a client's website recently and we used Divi as the base and a child theme for styling. Everything worked perfectly, life was good, and it was totally functional.

My client's hosting service moved her site from shared hosting to a private server. Fine. Shouldn't impact anything. At the same time, they added a bunch of plugins which stopped the style sheets and javascript from loading properly. The plugins they added were designed to compress files to make them load faster. Ultimately, the site looks awful as it's all just raw text random code strands, and the likes.

I disabled the plugins which resolved the issue on desktop but on mobile the compression remained. It's as though it actually modified the theme/core code instead of being a function of the plugin when it's enabled.

Then to "fix" it, the hosting company went in and did something which resulted in this fatal Divi error (pic attached). Before I restore the original backup of the site, does anyone have any suggestions for resolving this? It's a massive file and if there's a better fix than what will likely be a 4-6 hour re-upload of her site files, I'd rather do that.