A published form now ends with a short line under the form itself: the Magpie name, and an offer to the reader to make their own form for free. It sits outside the card, on the page background, and takes its colours from the appearance theme you chose, so it reads as a signature rather than a banner. It appears on the live form, on the preview, on a closed form, and on the screen someone sees after submitting.
On a paid plan, Magpie link in Form settings removes it from that form. The setting is per form, so other forms keep the link until you turn each one off, and the preview shows the result before you publish. On the free plan the link stays.