Separating preparation from review is a basic quality control. A second professional examines the work with fresh eyes, checks that figures are supported, and either approves it or returns it with notes. The separation only works if the reviewer did not contribute to the work and if the firm records exactly what was reviewed.
Software can enforce the separation. It can block contributors from approving their own work, preserve a snapshot of the workpaper and evidence at the moment of submission, and record the reviewer's decision against that snapshot. Later changes then create a new review rather than silently altering what was approved.