Attach (recommended) or Link to PDF file here:
[0 NIF MODELO 30.pdf](https://github.com/mozilla/pdf.js/files/7187486/0.NIF.MODELO.30.2.pdf)

Configuration:
- Web browser and its version: firefox nightly
- Operating system and its version: linux debian

Steps to reproduce the problem:
1. Open the PDF
2. Click on the button  `Rellenar Formulario` (top right of the first page)
3. There is the pop-up "Stay... or Leave...`.

It's a bit annoying from the user pov and it doesn't make sense (nobody wants to leave the form but just reset it)

It works fine when replacing  `""` by `"#"` here:
https://github.com/mozilla/pdf.js/blob/7082ff9bf876b98fbda118cdbd6267d3c0df6948/src/display/annotation_layer.js#L483

@Snuffleupagus, you changed this few month ago:
https://github.com/mozilla/pdf.js/commit/e2b6d79dee9ffd2aba715d6b3cb8fa143d86153c

do you have some ideas ?
elementData.userValue = event.detail.value || "";
              storage.setValue(id, { value: elementData.userValue.toString() });
              if (!elementData.formattedValue) {
                event.target.value = elementData.userValue;
              }
            },
            valueAsString(event) {
              elementData.formattedValue = event.detail.valueAsString || "";
              if (event.target !== document.activeElement) {
                
                event.target.value = elementData.formattedValue;
              }
              storage.setValue(id, {
                formattedValue: elementData.formattedValue,
              });
            },
            selRange(event) {