One of our faculty noticed that surveys in Canvas can't be officially anonymous. Students need to know that their feedback is actually anonymous for surveys to work. Right now, an anonymous survey can be made anonymous and then edited after the students have responded to make it no longer anonymous. This allows the teacher to see the student individual responses. A simple solution would be to grey out that button once students have started taking the quiz/survey just like some of the other features in the quiz/survey once the survey has been started.
I found a similar request in the archives:
This idea was considered when developing our product plan for Q3 2019 and is not expected to influence development within Canvas at this time.
This idea will remain open for vote.
If this idea is in the top 10% by vote next cycle it will be reconsidered.
Read more about the feature idea process: