Can you please check these few posts? It looks to me like copyleaks is giving false results. 
I have no doubt in mind that these posts are written by AI. Every post shows 100% detection by Copyleaks and GPTzero (except number 4, which shows 76% GPTzero and 100% Copyleaks) which IMO is the gold standard for detection.
Why do you think Copyleaks is giving you false positives?
Honestly, I'm a bit confused
. I've sent reports to the moderators, but they haven't been processed yet. Besides, the user is Brazilian, if I'm not mistaken, and here again there is a problem with the translator. In some posts, at least. And yes, you're right, I've seen these results too, but QuillBot doesn't give me confirmation in some posts, almost at all.