Right click menu doesn't get cleaned from old entries

Steps to reproduce:
Install Firefox' Multi Account Containers adding: https://addons.mozilla.org/en-US/firefox/addon/multi-account-containers/

Create Container. See that Containers sadly don't work. Uninstall add-on. But the right click menu still has an entry.

Expected behavior:
Clean right click menu.

Orion and macOS:
0.99.107-beta (WebKit 613.1.3) on Mojave

Image/Video:

Ok thats weird that the setting would persist after the addon is uninstalled.