I have a git repository that looks like this:

A1  -  B1  -  C1  -  D1  -  E1
           
             C2  -  D2  -  F2

The file changes in C1 and C2 are identical. If I run git diff C1 C2 then I get an empty result. Likewise, the file changes in D1 and D2 are identical.

The commit messages of C1 and C2 are different, and the commit messages of D1 and D2 are also different.

The hashes of C1 and C2 are different. Likewise, the hashes of D1 and D2 are different.

The changes in E1 and F2 are completely different.

I would like to get a repository that looks like this:

A1  -  B1  -  C1  -  D1  -  E1
                         
                           F2

I already tried git rebase and git rebase --onto and that just keeps the commits C2 and D2.

This is a fictional example. Here there are 2 commits that have the same changes. In reality there may be a few dozen or hundreds commits that have the same changes before the code diverges, and there is no simple way to determine how many without examining the entire history in detail.