Cannot save backup file in Vivaldi (a Chromium-based browser)

### Describe the issue

The backup file cannot be saved in Vivaldi (a Chromium-based browser).

**How to reproduce**

In Vivaldi, click on the Authenticator extension, click on Settings -> Backup -> Download Backup File.

Result: nothing is downloaded.

**Notes**

- Google drive backup also does not work. Nothing happens when clicking "Sign in".
- Reinstalling the extension did not fix the problem.
- The backup file can be saved in Chrome on the same system.
- Tested on Windows 10.

### Browser

Other

### Browser Version

Vivaldi 7.1.3570.50

### Extension Version

8.0.1