httpclient calling another localhost subdomain is failing,, c++, httpclient, windows

I have three core applications , and they are talking to each others using .net httpclient.

When I run them locally, I run them each under different ports, and they run ok under kestrel or rider.

one of them run under subdomin, and used to run it as subdomain1.localhost:8080 or subdomain2.localhost:8080.

everything was running nice, until yesterday (2021-06-08). my anti-virus Bitdefender started to block all calls for subdomains, and I had to create exception for it.
But the other application that didn’t have subdomain (localhost:7070) was called successfuly from the other twos with no problem.

but suddenly (maybe after windows update), I kept getting the error "No such host is known"
only on the subdomains.

the calls to the other service with no domain was good.

I switched off my anti-virus totally, and even switched off windows firewall, but still getting that error.

then I added this in hosts file subdomain.localhost

and it start to work again.

My question, any update on windows that disabled these calls.

my code is straight simple

 HttpClient client = new HttpClient();
 var data = await client.GetAsync("http://subdomain.localhost:8080/api/myservice/getdata");

Source: Windows Questions