The most common dialog copy is a bare "Are you sure?" It's grammatical but empty — it doesn't say what's being affected or whether it's reversible. Repeated often enough, users stop reading and just click reflexively.
A good confirmation dialog names the specific target ("Delete '2024 budget.xlsx'?") and states the consequence ("This can't be undone"). For reversible actions, skipping the dialog entirely and offering undo-after-the-fact (see optimistic-ui) is often the better call.
The demo's ✕ just repeats "Are you sure?"; ✓ packs the target and the consequence into one sentence.
When to use
Reserve dialogs for hard-to-reverse actions like delete, send, or pay. If it's reversible, consider act-then-undo instead.