Fix Corporate Site Loading Issues

My corporate website, hosted on Hostinger and connected through Cloudflare, is experiencing severe loading issues on multiple pages.

- The issue initially occurred only when Cloudflare Developer Mode was OFF, but now even in Developer Mode, the pages are breaking.
- Adding ?cache at the end of the URL loads the correct version.
- I need an expert to diagnose and completely fix the issue at the root.

Ideal skills and experience:
- Expertise in WordPress (if applicable), Cloudflare, and Hostinger.
- Strong problem-solving skills to identify and resolve complex web issues.
- Experience with debugging caching problems and ensuring proper site functionality.

Please provide a detailed plan on how you would approach this issue.