Notification saying "Your iCloud being Hacked" poping up on my Mac.

brettwa wrote:

I’ve done that on safari as well as google chrome but it still keeps popping up.

I believe if it was accepted in Chrome you had to do an additional step that required resetting to factory settings, but I will continue to look if no one provides specific Chrome details. You may want to check if anything is at  > System Settings > Notifications.

Here is the Support Article that deals with these notifications to see if this is what you are seeing. This one just discusses Safari.

Stop unwanted Notifications - Apple Community

Go to Safari > Settings > Websites > Notifications, and remove all websites allowed to send Notifications.

These are scams that appear from a website. When you visited the site, it asked if you want it to send you Notifications. If you allow that action, some sites will pop up these fake messages.

iPhone or Mac?

Maybe provide a screenshot of what you are seeing.