Hi there,
A 524 timeout doesn’t necessarily mean that your server is overloaded. It could also be that your web server didn’t respond in time because of an issue with your website code. In my experience, it could be the case that some third-party loaded slowly or some condition wasn’t met in the code and that therefore no response was sent. This in turn could let the web server believe that it still needs to wait and hence times out.
We can provide you with further information on what your web server responded, if you open a ticket with us, but that’s about all we can do. If you want to check if it’s Cloudflare related, try disabling the 
Proxied mode (set it to 
DNS-only), test it, and if it loads slowly, it’s probably something on the origin. Otherwise, it could’ve something to do with an error that occurs when Cloudflare connects to your origin.
Hope this helps.