No, it makes sense. "Copy this" buttons are common on websites, but probably require a button click to initiate. Since you clicked on a button, you provided the input necessary to copy to the clipboard.
Theoretically, a bad actor could have a site or even inject code onto a site with an innocuous looking bash command, but upon copy injects say, rm -rf ~ \n
Seems like this requires you to select some text (which includes some text that's been hidden using CSS tricks) and copy it. So it's not like the website can just arbitrary write to your clipboard without your interaction? (Still, this is kinda scary and I didn't know about this.)
Is it? When I click the "Write" button, it turns green, but when I click "Write (delayed)", after a while it turns red. So it seems (at least on Firefox 87) even the clipboard write API is restricted to user-action event handlers.
It’s also a privacy issue. Google’s Firebase Dynamic links is using it non-maliciously to survive app installs for deep linking(when the app is not installed it helps you redirect the user to the correct screen after the install), however any webpage can actually put something on your clipboard and match you on an app by reading your clipboard.
With iOS14 at least we can tell when apps are reading the clipboard.
Seems like a great method to social engineer people into copying to clipboard something that will install a trojan, get them to open a command prompt and paste it, in the general concept of curl piped into a shell.