Website Giving "Bad Gateway" 502 Error randomly when on Cloudflare network

Hello, I am using Cloudflare with IONOS, from last 2 days my website is giving 502 bad gateway error randomly, like if I open 5 pages, 1 of them will get that error and when I refresh that page it works fine.
I have tried pausing cloudflare and it starts working fine again.
so problem might be from Cloudflare side, my website url
problem happens for static files also like images and css js file.

Hi there, thanks for reaching out to the Cloudflare Community!

502 errors are mostly caused by a problem connecting to an upstream server. In most cases, the server is returning the 502 due to excessive load or crashes. When this happens, you will see colour page with Cloudflare branding and the Error 502 Bad Gateway.

Further steps to investigate this are available here: