I would not put too much weight on fraud-score checkers in the first place.
Different services use different databases and scoring criteria, update them at different times, and can easily show completely different results for the same IP. A fraud score can be a useful signal, but treating it as the main measure of proxy quality is a mistake.
The only test that really matters is whether the proxy works properly on the exact platform you need it for. An IP can look “clean” in every checker and still fail on the target site, or show a poor score and work perfectly fine.
As for DNS leaks, that is often caused by the user’s browser, operating system, IPv6, WebRTC, or DNS configuration rather than the proxy itself. I would test the full setup first before assuming the provider is the problem.