Have you reported this issue? https://testpilot.firefox.com/ https://support.mozilla.org/en-US/kb/test-pilot-test-firefoxs-experimental-features SUMO community discussions; Firefox Test Pilot https://support.mozilla.org/en-US/forums/contributors/711977 Test Pilot is controlled from this page: https://testpilot.firefox.com/experiments/ From there you can disable the experiments one-by-one and also provide feedback about each feature that you disable. Use the Settings button to access the menu for support and information about Test Pilot. https://discourse.mozilla-community.org/c/test-pilot