Steps to reproduce:

1. Under Container, choose a proxy for Incognito, save settings
2. Open a new Incognito window, proxy would be in use (as intended)
3. Under Container, choose nothing (blank) for Incognito, save settings
4. Open a new Incognito window, proxy still in use (should no longer be using proxy)

Uninstalled addon, re-installed, problem persists.

Reverted to 8.9 for now.