To reproduce:

1. Create a new game
2. Go to "Manage Games" and add another game
3. In the second game, go to the Edit mode. Add any comment.
4. With edit mode still active, use the "Go to Previous Game" keyboard shortcut (CtrlOrCmd-PageDown) to go to the other game.

The comment is still shown and if you exit Edit mode now the first game gets that comment as well even though it shouldn't.

This also happens when you have a single game and add a few moves. Then, for any move, go to Edit mode and add a comment. Don't leave the Edit mode but select any tool, like the triangle tool. Then use arrow keys to go to other moves. The comment is still visible even though it shouldn't be.