Example (warning: NSFW!) https://iamover18.net/posts/3801
The user is definitely marked "NSFW": https://iamover18.net/u/sex as all of their posts are showing up with the NSFW flag, but apparently when I went to reshare one of their posts it came across without the NSFW flag.
This is a serious bug.
It seems it's not related to the re-share: Some of the posts of that user do not show as NSFW at all. Check the profile on diasp.eu: https://diasp.eu/people/f22256b03cd101328dc142010af01ad6
Related to #4584 (although the issue is more clearly explained here).
I don't think this is an issue anymore. With test posts, all posts of a profile marked as nsfw were displayed with the nsfw-shield after reshare as well.
It's still an issue, if the nsfw flag of a profile doesn't reach a pod (especially since it isn't part of the initial webfinger/hcard), then posts without #nsfw tag but from an nsfw profile are still shown without nsfw warning.
The nsfw flag should be attached to the post if the profile is marked as nsfw. This also helps when people unmark them as nsfw, so old posts don't become visible.
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It's still an issue, if the nsfw flag of a profile doesn't reach a pod (especially since it isn't part of the initial webfinger/hcard), then posts without #nsfw tag but from an nsfw profile are still shown without nsfw warning.
The nsfw flag should be attached to the post if the profile is marked as nsfw. This also helps when people unmark them as nsfw, so old posts don't become visible.