Edge-based site taking over global Windows keyboard shortcuts

I had a pretty weird experience this morning when looking for a product manual. The site that I went to had either been hijacked or was deceptive in purpose and transformed into one of those “Microsoft security alert” sites with the robotic voice.

But however it happened, Edge went full screen and blocked access to all keyboard shortcuts such as Alt+F4, Ctrl+Shift+Esc for Task Manager. It’s my first experience of something running in Edge being able to take over the system so completely. Is this a new thing? It’s concerning if so. The only thing that worked was Ctrl+Alt+Del.

Anyone else seen this before?