Well, the problem isn't the platform. You can actually see many Q2A websites running Adsense ads on Q2A sites list.
This is most likely an issue with your domain.
There's a number of things that could result in Google viewing your domain as malicious
First of all, check the basics.
Are you running any other scripts on that same domain?
For example are you running one script on (domain.com) and then running Q2A on a subdomain (q2a.domain.com) ? If so, make sure it's not malicious, of course. This other script might be the generating point for this issue.
Weird/Unusual domain extensions
Having weird domain extensions can be detected as a malicious website (ex: http://ghu.afu.td). A website solely created for malware purposes.
Make sure you have an SSL Certificate for your domain, and force https to be used, instead of http.
Make sure your external links also link to https pages and are not linking to any third-party blacklisted websites.
"Have sent 3 websites with none of them approved"
If all sites are hosted in the same domain (q2aSite1.domain.com , q2aSite2.domain.com , q2aSite3.domain.com) all of them will get the same response. Being approved or being disapproved, because what counts is the main domain name here. If your domain.com is eligible, then all of your domain is eligible. Meaning you can display ads all over the domain's tree. Main domain, subdomains, subfolders etc...
Read More: Unwanted Software Policy
After verifying everything, making the changes and swapping to (HTTPS) protocol, clear your website's cache, wait 10-12 hours, check if everything looks good and ask for another review.