How to convert GitHub squash and merge commits to merge commits?

Squash merges are destructive operations and there is no way to reverse them.

It is a really, really bad practice and you should stop using them.

If you are lucky you might find traces of the original branch that was used to create the pull request, so that you could resurrect those commits and create a new branch on the last commit. With that you might change your main branch by discarding the squash commits and replace with real merges using reset, rebase and/or interactive rebase.

To hunt locally in your repository you can use git reflog or gitk --reflog to find "unconnected" commits that has not been discarded yet.

On the remote side I think github has some history references to commits in the pull requests that you might be able fetch.

This task will not be trivial but it will be a great learning experience for you. NB, start by making a copy of the whole repository directory so you have a backup to fall back to or to start over again.

I solved this by doing git reset --hard to before my first PR merge.

Then, I cherry-picked the individual commits of each PR and did git push.

This solution doesn't exactly use merge commits like GitHub, but I found out I actually like a linear history more.