We have two pieces of functionality that can save data entered in the form before the user submits it, thus helping prevent any data loss. Both of these options can be found in the Save & Continue section of your form's settings:
Save form progress: Enabling this toggle will automatically save data for all fields in the user's browser. This temporary data is not saved in Airtable until the user submits the form. This feature is only available when creating new records, which also means that it is not available for forms that use a login. Since the temporary data is stored in the user's browser, the user can come back to the form at a later date and still find their previously entered details, provided their browser hasn't cleared the site data in the meantime.
Save & Continue: Save & Continue mode will keep sending the data to Airtable while the user is still filling in the form. This can be done either automatically (when Save Mode is set to Auto), or manually by clicking on the save button or when going to the next form page. These non-final records should be considered to be in Pending status or Draft mode. The only indicator that the user actually submitted the form is by looking at the Confirmation Checkbox Field. You can find out more about Save & Continue mode here.