• VSCode Version: 1.38.0-insider
• OS Version: Windows_NT x64 10.0.17134

Originally mentioned in #69651 which covers a similar issue with tab labels.

Steps to Reproduce:

1. Download branch at https://github.com/gjsjohnmurray/vscode-extension-samples/tree/show-69651 which contains a read-only variant of fsprovider-sample.
2. Build and run fsprovider-sample
3. Run these commands:

• MemFS: Setup Workspace
• MemFS: Create Files

4. Go to Explorer view and open any of the files in the tree.
5. Observe the ' (read-only) (read-only)' suffix on the filename displayed in the window titlebar.

@isidorn I am preparing a PR that will fix this issue.