Anyone Face this Issue When He Work With Proxy

Hi guys hope all doing great,

I have please a problem when today i connect to my proxy is showing the DNS of the proxy on "Whoer" :




But before is doesn't show me any DNS on "Whoer" all things was working before :



I ask the manager of proxy and they told me is not from the proxy is from the browser leaks or something like this and he give me a screenshot to prove this, the DNS is not showing on him

I have search a solution on google how to hide this but all they give to use a VPN .... i didn't find anything to fix this hope someone can help me.

Thank you