Is the New DNS Rebind Test Correct?

I go to DNS Rebind Test: Secure Your Network from Hidden Threats | Control D https://controld.com/tools/dns-rebind-test?ref=controld.com

The results are that I am vulnerable. “Your DNS resolver appears vulnerable to DNS rebinding attacks. Large timing variation detected (5.90s difference between fastest and slowest requests), suggesting inconsistent routing that may indicate rebinding.”

That is scary, especially because my enterprise-grade BSD-based router has a setting that prevents DNS rebinding attacks that is turned to on.

However if I go to https://bigdig.energy/ at website that is affiliated with Control-D (theirs a Control-D logo on the home page), I get different results.

Bigdig.energy using the same PC/same router/same browser says:
DNS Leaks: None
Multiple DNS servers from the same provider were detected. Your DNS configuration appears to be consistent and secure.

One of the websites is wrong. Which site has the correct results?

Thanks.