Using residential proxy leaks dns

So I'm trying to use http/https proxy that i got for myself and each time I use it leaks my dns. Like the ip changes fine but tests show my dns too. Is that normal with proxies or I configured it in a wrong way or perhaps it's my provider of proxy. I have ip address, port and login, password.

Need some answers or help with configuring it correctly on firefox or chromium.

dns leaks privacy proxy residential proxy