Hi
I am not able to open Power Portal Designer and getting some API errors in the console.
Steps to recreate this issue
1. Open your Power Apps env by visiting make.powerapps.com
2. Edit the portal app you have in your environment
3. White frozen screen will appear.
Note: Model-driven app and Canvas App are still editable and only Portals not editable. I have checked this on personal and customer environment both. Refer the screenshot.

Thanks
Devika