Unable to access my website and cpanel

It gives 521 error.

Error 521 occurs because the origin web server refuses a connection from Cloudflare. More specifically, Cloudflare tried to connect to your origin server on port 80 or 443 but received a connection refused error:

Some of the times this error is caused by the web hosting provider to be blocking the requests Cloudflare sends to the server. It can happen if it has a firewall or any device that may be limiting the requests from Cloudflare to it.

Also, I’m getting this error on my cloudflare dashboard page:
API Request Failed: GET /api/v4/accounts/694c91*************************8/flags (502)

I am not clear on the operation you are attempting. The accounts API endpoint can provide account details if you enter its ID as a parameter, but I don’t see a flags endpoint after it.

Hope this helps you moving forward with this case.