Don’t panic - you’re just seeing a persistent malicious popup. If Safari has been force-closed, there are things we can do. Don’t under any circumstances respond to pop-up messages purporting to be from Apple; they’re not!
First, we’ll erase your Website data to clear-out any persistent links:
Settings > Safari > Clear History & Website Data
Now we can try to prevent a recurrence. From the Apple App Store, I recommend that you install the 1Blocker App. Just search for it by name in the App Store. Here’s a direct link, but your regional App Store may differ:
https://apps.apple.com/gb/app/1blocker/id1365531024
1Blocker is a very effective Content and Ad blocker - with an excellent reputation. The free functionality should provide good protection from unwanted intrusion, but you might benefit from the modest subscription to enable full functionality.
There are some additional things we can do with DNS settings if additional protection is required. Let us know if you want to explore this option.
I hope you find this helpful.