Yes, please check if you have disabled the feature Enable Editing after Submitting Application from the application's general information
and then ensure that you have updated the section lock rule as well, update the Lock After Submit to Inherit from Application so that the section will be locked for the users as soon as they submit an application.
Note: Please set the Lock After Submit to "Yes" for the post-acceptance sections as they have a separate submit button and will be submitted after the awarding.