Prolific will only recruit the number of participants you requested when setting up your study.
If you check your submissions list, the total number of submissions in either 'awaiting review' or 'approved' status should match the number of submissions you originally requested.
Submissions with a 'timed out' or 'returned' status do not count towards your total number of submissions and do not require any further action.
As a result, you may see more submissions in your submissions list than you originally requested. This usually happens when a participant times out or returns their submission, and another participant is automatically recruited to replace them.
However, if you manually approve any timed out or returned submissions after data collection has ended, these will count as additional submissions beyond the number you originally requested.
This means you may end up with more approved submissions than planned.
If you have more submissions in your external survey software than on Prolific, it may be because a participant accessed your external study link more than once and completed the study multiple times.
You can find further guidance here: Enabling multiple submissions to your study