Unless you have any indication that the Qt downloads really contain malware, which we can be pretty sure they don't, this clearly is a bug in Chrome and only the Chrome developers can fix it. The Qt devs probably cannot do anything.
So-called "anti virus" software can be a major annoyance for software developers. Believe me, I know what I'm talking about. I get like a dozen e-mails from angry people complaining that my software contains malware every single week - just because their "anti virus" program triggered a FALSE POSITIVE. Usually these people are quiet very quickly when I tell them to re-check the file at VirusTotal and they notice that 49 out of 50 anti-virus scanners confirm that the file is clean...