That sounds like a AVG false reporting and you need to contact AVG support about this if that is the case.

This could occur if your home page, or an open tab (if you restore your previous session), or an add-on sends a request to the blocked site. Can you see any connection between your home page or restored active tabs and the blocked site?

No, the only tab I have that opens is the notification. Maybe it is an AVG problem as suggested.

here's the screen

Does that "hmining.mobi" address show up if you launch a new window (Command+N)?

If so, please check the home page setting to see whether that or some other unexpected address is stored there as a custom URL or under the control of an add-on. See: How to set the home page.

When I search on the web, I see posts on the Apple forums about it infecting Safari many years ago. In case it could have a presence outside of the browser, to supplement AVG, you could scan your system with Malwarebytes Anti-malware for Mac: https://www.malwarebytes.com/mac

Yes, that website was in the home page url. I deleted it. Thank you! Rob

Hi Rob, thank you for reporting back. Web pages can't change your homepage, it is usually done by either an add-on or an external program. Please be alert for anything strange and clean as needed.