subtree split fails to remove not relevant commits

Hello,

What did you do before the bug happened? (Steps to reproduce your issue)

`git subtree split --prefix=${project_path} --branch=${BRANCH}` . As part of the parent project we developed a couple smaller ones. Now it was time to release them separately. Most splitted as expected - first commit in the history was about creating a sub-directory. One sub-project has an issue - history wasn't erased, it contained full parent project history, and only commits starting from creation of the sub-directory have "contents" changed.

What did you expect to happen? (Expected behavior)

When I do "git log --oneline -- $path-to-usb-directory" I have 21 commits in the history, so I expect to receive this history in the resulting, filtered, repository.

What happened instead? (Actual behavior)

Full history of the parent project is visible. Originally encountered on 2.17.1. Then replicated on 2.25.0 and the one below.

At the moment the parent repository is not publicly accessible, but I can share it if this will be useful for debugging. It also has the script that splits sub-projects.

[System Info] git version: git version 2.35.1 cpu: x86_64 no commit associated with this build sizeof-long: 8 sizeof-size_t: 8 shell-path: /bin/sh uname: Linux 5.4.0-104-generic #118~18.04.1-Ubuntu SMP Thu Mar 3 13:53:15 UTC 2022 x86_64 compiler info: gnuc: 7.5 libc info: glibc: 2.27 $SHELL (typically, interactive shell): /bin/bash

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