Good but it messes with other site's animations. You can fix this by now allowing it to run on other sites but it has to be turned on manually in firefox's addon manager tab
Are you sure better canvas is causing this? I don't know of anything in the code that would prevent you from submitting an assignment. If you mean the submit button is missing, then check your dark mode colors - they may all be the same color which could make it appear like the button is missing.
