In SDC, if you select a date-type property, such as P571, and begin typing, a popup appears to display the date formatting.
There is no X or way to close this popup in the interface. For usability, this pop-up should be closable, as it is on Wikidata, so that users can reduce clutter on the screen if they don't need this popup (especially wen entering many claims at once). This is what Wikidata looks like, first open:
And closed:
