Why does the number of commits for the project not match the sum of commits from the participants?

Question

This project shows that the fixations were made in 1993, but clicking on the depositors shows that their half is less than half, only 925.

Why the discrepancy? Each branch has over 1800 commits.

Answer 1

In the Repository Repository help page

The Contributors column shows the commit made by the top 100 participants throughout the life of your project.
This graph does not contain commits or commits with zero changes .

If there is a lot of PR for this project, this may explain the delta (or part of it in any case)