Twitch still kinda extraordinarily blows though considering the circumstances, so like, it *might as well be* cats on keyboards anyway.

As someone that uses a Yubikey daily and have accidentally tapped it more than once, this is like 98% what's happening here. You tap the button on the USB and whatever textbox you were clicked into will receive "gibberish + Enter key", and the gibberish usually looks a lot like what's pictured.