I am dev. I'm testing and debug in a code. Sure, I use the console each day of my work, a hundred times per day, and I'm incredibly annoyed to see this Self-XSS warning and type allow pasting each time I open the console.
Early at lest I had an option to toggle "Show Self-XSS warning" in Experiments, it worked at least until you close the browser, but now after yet another great "security" update they removed this toggle. This is pissing me off, I don't know how to rid off this message now.
The Dev has removed the self-XSS experiment (but kept the functionality). Now the only way to disable the warning is to type allow pasting when you paste code.
But good news is once you typed allow pasting, the warning will be permanently disabled for the same profile where you typed allow pasting. Even if you close the browser, the warning will not show up anymore. My suggestion is you can just stick to one profile for your testing if possible.