So this post from lemmynsfw.com just popped up in my feed. It is not tagged as nsfw although it obviously is. I have tried attaching a screenshot but Jerboa throws an error. I have nsfw material turned off in my account settings, so this wouldn’t happen if the post would be tagged properly. I’m using Jerboa. I could just ban the whole community but it is not the solution in looking for, because the ban works on app level and I have separate accounts for separate needs. Also banning the community is a reactory move and I would need to repeat that for every offending community in the future. That means that my feed would still be getting occasional nsfw material. Please advise.
As far as I can tell mods are swift in dealing with reports. And even though the rule exists there will always be people that ignore those rules. There is no way to block whole instances at the moment and without the NSFW flag, there is no technical way to see that the post contains NSFW image.
In addition to reporting the post in question you could also block the user if you suspect that they are posting without the NSFW flag regularly.