Import of project shows a different git repository size

Summary

We're currently importing projects from GitHost into GitLab. Amongst other problems I also see that the project size differs each time.

Steps to reproduce

Import a project from GitHost.

What is the current bug behavior?

Size of imported project differs from original one.

What is the expected correct behavior?

Size is expected to be the same.

Relevant logs and/or screenshots

Output of checks

This bug happens on GitLab.com.