Relevant:
How to address possible copyright issues in Thomas Turin question
Familysearch terms of use (2018) and "ownership" of information?
Point the 1st: It is not our job (as moderators or users) to police the copyright/terms of service of the providers of source documents.
Point the 2nd: Posters here have agreed to the SE Terms of Service, which includes giving SE an irrevocable licence to publish material you contribute, including images. However, if they've breached somebody else's ToS or copyright they can't grant that licence. They might sail under the radar or the company who own the rights in whatever was published might find out and issue a DMCA to SE, who would then take the material down and might also remove the offending account. (see https://stackoverflow.com/legal/acceptable-use-policy)
Point the 3rd: All providers of sources have different ToS, so posters will have to investigate for themselves whether they're allowed to publish what they want to publish -- there's no way we can offer definitive guidance in all cases, and especially in complex cases where (for example) Government Organisation A has licenced images of its material to Commercial Organisation B, whose terms of service for the image may override the terms of Government Organisation A...
Final point: We have in the past suggested publishing either a cropped part of an image (only enough to make the question make sense) or a substantially blurred image as the most sensible/lowest risk route forward (ideally with a link to the original image that it was derived from, thus attributing the material clearly.)
