Actually, this is a feature I added, that hides the cover picture for articles that have negative r_shares. Basically this cover was hidden as NSFW because the downvotes outweighted the upvotes. I do this to protect stupid stuff from being displayed on dtube, this way the community (aka whales) can easily control a bad content and downvote the hell out of it to hide it.

I don't believe this is censorship, anyone can have the option to 'activate nsfw fully' in the settings.