An instance's admins and mods are usually attentive to see if there are posts that violate their Code of Conduct (CoC). However, it is ridiculous to believe that they are going to be a 100% effective filter because they cannot monitor all timelines at the same time 24/7.
Therefore, if you see a harmful post that violates the CoC of your instance, report it to your admin. Prioritize the use of the native tools of the platform, they facilitate the action, but in case they are not available (I still can't find how to report from Friendica, for example) establish a contact with your mods or admins with a message explaining the situation.
Reports help alert admins and mods of unknown violations. Remember that they cannot solve a problem if they do not know that it exists in the first place.
Information is power. The more details of what happened, better decisions can be made and other instances with similar principles can be warned of a possible danger.
In this instance, all the reports received will be read and carefully analyzed to take the best possible action. We appreciate your help reporting people who break the CoC.