I think what you’re seeing is that, as things stand, Glitch overwrites parts of your local git config every so often. I’m not sure exactly what the cycle is, but if you looked at git config -l you might see more than one value set and cat .git/config will show you what’s set locally and is being used in the commit messages.
I haven’t tried to set up a credential.helper yet, but for the user.email setting I have a manual process I use to control the commits that includes resetting the user.email value before I commit.
I’m working on making this happen automatically for you, but it’s harder than you would think. There’s some infrastructure refactoring happening right now that will make it easier, so I’ll do it after that.