MacBook Pro notifications about being hacked

You just allowed a website to send you those fake Notifications. All you need to do is open Safari, then go to Safari > Settings > Websites > Notifications, and remove all websites that you have allowed to send you notifications. Problem solved!

In addition, you can uncheck the box there that says "Allow websites to ask for permission to send notifications".

Stop unwanted Notifications - Apple Community

Those notifications are generally not written using proper grammar.

"Your computer IS Infected. " should actually be written:

Your computer is ABOUT to be infected, ...

... as soon as we panic you into doing something stupid,

like responding to this garbage notification.

Make the same change for any other Web browser you use. The controls may be in different places, but the idea is the same.

I have seen Windows notebooks where scammers were sending these types of notifications so fast as to make the computer unusable. You could hardly even get into the settings screens to block the scam messages. But once you did, the computers were usable again.