modified property (https://final-form.org/docs/react-final-form/types/FieldRenderProps#metamodified) which is basically like a Tamper Sticker, and is useful for Saving Indicators on autosaving forms (since it lets me handle the case where the user changes a field, autosave kicks in, the indicator shows it's been saved, and the user changes their mind and puts the field back to the initial value... RFF uses equality to determine the pristine state, as well as the dirty state).