change_authors.sh

python git_filter_repo.py --commit-callback "
if commit.author_name == b'full name of the previous author':
    commit.author_name = b'username of the new author'
    commit.author_email = b'email of the new author'
if commit.committer_name == b'full name of the previous author':
    commit.committer_name = b'username of the new author'
    commit.committer_email = b'email of the new author'
"

In my case, the previous author was just my full name so it wasn't connected to any account, and therefore didn't have to change an e-mail for that.

have the git_filter_repo.py in the same folder of this command, and run this command in a terminal that supports multi-line string copy-paste like MobaXterm. Then run the following command to push the changes to the repo.

git push -u origin master --force

in my case, I moved my previous repo from gitlab to here, so the main branch was called main.

git push -u origin main --force