How to prevent social media swarm responses to a survey?

The usual duplication (ballot box stuffing) detection prevents multiple responses from the same user for pre-survey exclusion, or requires that the user complete the survey and be excluded/flagged afterward after the response appears to be a duplicate. We have recently encountered a different issue that we would like to prevent in the future. We provide anonymous links with an access code, but someone posted their code to social media. How can we limit the number of responses per code? I’ve poked around in workflow and survey flow but found nothing that seems to be suitable.