git log -p path/to/file doesn't show all changes

I want it to show all changes (commits) to the specified file, but it doesn't do that. It only shows some of them. I guess it has something to do with merging, but I don't see what could be wrong here. Can someone explain?

UPD I was able to reproduce my specific issue in the test repository:

#!/usr/bin/env bash
set -eu
rm -rf 1
mkdir 1 && cd 1
git init

mkdir 1
echo m1 > 1/m1 && git add 1/m1 && git commit -m m1

git co -b b1
echo m11 > 1/m1 && git add 1/m1 && git commit -m b11
echo m1 > 1/m1 && git add 1/m1 && git commit -m b12

git checkout master
echo m2 > m2 && git add m2 && git commit -m m2
git merge b1 -m 'merge b1'
git --no-pager log --graph --oneline --decorate --all
git --no-pager log --oneline 1

commit b11, b12and is not listed in the last command.