Why do browsers trust Cloudflare shared SSL certificate?

So I chose to use Cloudflare's shared SSL certificate with CDN, now the website I sign up for has this certificate shown in the browser:

SSL Certificate

The "issued to" domain is not my domain, this caused a problem:

The https post API of my program thinks my website does not have a valid certificate

However, when I open up my site with Chrome browser, the secured icon shows up:

https valid icon

It seems that the browser thinks the Cloudflare shared certificate is OK,

while the "issued to" domain is clearly not my domain

So the question is:

Why does the browser trust the shared SSL certificate with "issued to" not matching my domain, while the WebRequest from a C# program does not trust?