Agreed, and the silent ones hide in the tooling too. This week we found that Playwright's element boxes are wrong inside an iframe with CSS zoom on it: it put a heading at x=1427 in a 1280 px window. Seven of our e2e tests failed loudly on that, which was fine. But our screenshot script used the same boxes to decide whether a page fit the pane, concluded it never did, and quietly zoomed every preview down to 40 %. It passed and produced pictures, and only a person looking at them noticed. It now measures inside the frame instead (getBoundingClientRect against the frame's own innerWidth).