I’ve just found that the survey complete page will stay if you launch with the original URL.
https://run.pavlovia.org/pavlovia/survey/?surveyId=60c04d2e-161f-4899-917c-423ff2d2a649
instead of
https://run.pavlovia.org/pavlovia/survey-2024.2.0/?surveyId=60c04d2e-161f-4899-917c-423ff2d2a649