At my high school most of my teachers didn’t allow cellphones in class, and would take them away for the period if they caught the student more than once.
There isn’t a lot of need for cellphones in a classroom, especially if the students have access to school laptops/computers.
It depends on what the community is about. If it’s a community/instance that features a lot of opinionated talk, downvotes should be off to avoid those with different opinions being downvoted and hidden. On a note advice based/general community I think they should be left on.