When I’m rewording a commit (via the Edit Commit Message command), sometimes I’m partway through explaining something and I want to quickly check one of my changed files. When I click on the tab for that file (which will be one of the tabs to the right of the Summary tab that I’m editing my message in), and then click back to Summary, all my edits are gone.
This can be very frustrating if I’ve just spent a bunch of time on my commit message (I try to follow https://chris.beams.io/posts/git-commit/ and have good commit messages).
I try to remember to copy my commit message over to Sublime Text before making my edits, but I forget often enough that it’s still annoying.