Hi there!
As discussed in the chats as well, this really doesn't sound like a case of anything being "compromised", or there being a security issue. On a surface level, do keep in mind that if you'd been compromised, that kind of sophisticated attack really isn't the kind of leave behind blatant evidence of itself, but I digress.
What is most likely to have occurred here is that your VPN disconnected (due to a crash or some other reason - unclear) and because block connections without VPN is enabled by default in GrapheneOS, Tor Browser stopped being able to access the Internet, and therefore couldn't load the page. It's hard to tell what happened with the "antivirus" app, since I don't know what app you use, but if it also relies on the Internet in some way, that may also explain that.
As I touched upon in the chat rooms as well, I hope you reconsider whatever "antivirus" app you're using. They're worse than useless on AOSP and often require outrageous permissions like the accessibility permission to "work".