After a hotfix is made on dev and cherry-picked to main, the main→dev backmerge PR still shows the fix as changed. The PR page is answering a different question. Two git commands show what the merge will actually change.
An in-depth analysis of the disadvantages of squash merge in Git, why it leads to loss of information, and why normal merge is always the recommended approach, with examples from the Linux kernel and other successful open-source projects.