Hello,
For clarification, you're talking about scenarios where a game developer uploads a game that opens a browser window? I don't think there's much we can do about this stuff. I think many platforms and software have the risk of opening a link you don't expect. We can do the best we can to automatically detect issues, but something like this seems like a very isolated case. I would open a report for the project page and we can investigate. itch.io is an open publishing platform, although we have reports and automated scanning, I still recommend using your judgement to determine if something is worth downloading.
Projects are now being packed which either contain links that areinstalled on the desktop (Such as Falcoware)
We run an automated virus & malware scanner over files uploaded and we've been banning these people as we detect them. If you spot something we missed please send a report from the bottom of the game page.