When you make a change in a linked worktree, that change is automatically reflected in the main worktree!
It makes sense: the linked worktree doesn't have a .git directory, so it's not a separate repository. It's just a different view of the same repository.
You can almost think of a linked worktree as just another branch in the same repo, but with its own space on the filesystem.
Run git branch from your main worktree, then answer the question.