以防有人***执行类似任务.=>解决方案:最终，我得到了服务器逻辑，该逻辑将用户角色更改为禁止"，并添加了该角色以访问_users DB的角色.这样，被禁用户将完全失去对其他数据库的访问权限(请求已注册"角色)，并且必须等到服务器将其角色更改回有效的角色.

In case somebody stepped down here for similar task. =>solution: Finally I ended up with server logic that changes user role to "banned" and adding this role to access roles of _users DB. This way banned user completely loses his access to other DBs (which request "registered" role) and has to wait until server changes his role back to valid one.