Just to add to the giant pile of anecdotal stories here, Google has been on Gmail labeling all links to the 350,000 Neocities sites as "potentially malware" for a while now, despite the fact that we don't allow uploads of executable files so that's basically impossible. We've only had one valid malware report in our 7 years of operation (zip embedded in a gif file, which I now know how to detect so it's fixed).

There's nobody at Google to contact, so I have no idea how to fix it. I used to have a friend at google I could ask for special help from (this made me feel awful), but they no longer work there, so I guess I'm just screwed until they actually get some sort of official support channel, or somebody at the company that sees this message (hi!) fixes it somehow (thanks!).