Restored old site but new errors shown

I’m pretty sure CI 2.x is only compatible with PHP 5.6 or lower. I would be surprised if it worked with PHP 7 or 8. Upgrading to CI 4 is mostly a rewrite of your website. But if you don’t want to do this a the moment, you can at least upgrade your website to CI 3.x and run it with PHP 7. There’s not a lot of breaking changes between version 2 and 3. I’m not sure if it will work with PHP 8. It’s an old version that don’t gets updated anymore. But it work well with PHP 7.

That's good information. I might be able to request PHP 5.6 from the web host, or like you say recode it in CI 3 instead. The strange thing is that we were using this website only last year prior to loosing it due to someone not paying the bills. I don't think it was running an old version of PHP.