@thor @mjdxp But it's w3m — no big deal, I can close it right away.
Super+Shift+B opens Firefox, Super and Shift are hard to press at the same time by mistake, but it's B, because it's also a browser. Likewise Super+Shift+I opens Firefox Window with Element, Super+Alt/Option+I runs gomuks — a lightweight TUI client, I is for IM.
Destructive window operations are also Super+Shift: Super+Shift+X closes current window, Super+Shift+Q exits Sway.