Vim mode u key can undo partner editings

Description of the problem:

When I'm developing a project and sharing this project with another person. If the editor is the default one, the Ctrl+Z key works perfectly fine for both of us. My Ctrl+Z undo my editing and vice-versa.

However, if I'm using Vim mode and I press the equivalent to Ctrl+Z inside the Vim mode (which is the u key), I'll undo my partner editings as well. It doesn't feel like that's the way it's supposed to work since when I'm not using Vim mode it behaves differently, so I'm reporting this behavior as a bug...

To Reproduce (I was using the Vim mode on Chrome)

1. Share a project with someone and edit this project at the same time with this person
2. Activate Vim mode
3. Ask the other person to write something on the project
4. Press u and it'll behave like Ctrl+Z, but instead of working only for your editings, it'll edit yours and your partner's editing as well

Start by reproducing the issue with a shared project in Chrome, Vim mode enabled, and edits made by both collaborators. Trace how the Vim-mode u key routes into undo and compare it with Ctrl+Z; done means undoing only the current user's edits without affecting the partner's changes.