As of v2023, the current placeholder text for document fields is "Drag-and-drop your file or click up...". One of the most common questions I get is why drag and drop isn't working. The answer is always that they haven't saved the record yet.

It would be really nice if the placeholder text was "Save the record to upload a document" when record is not saved and then it switches to the current one telling them to drag and drop or use the up arrow after the record is saved.