Having no edit access to a task does not prevent all changes

Dear all
I am facing the situation that I revoked all edit access to a task which prevents changes to the task only definitions, but any user with kanboad user role can still do additions (subtask, links, comment, documents, screenshots) or duplicate or move the task, what would be prevented by other restrictions and doe snot work as drag&drop.
Did I miss something or is it meant to be like that or did I detect a potential flow?

I am not sure if I understood your question.

If a user or group gets the “project viewer” role in a project, they should only have read access.

Docs: https://docs.kanboard.org/en/latest/user_guide/users.html#user-roles