Someone keeps uploading addons to the Steam Workshop without the owners' permission. Their Steam username is lexar1616, and everything they've uploaded to the Steam Workshop is something that someone else made, with the description "this is a port from the spaceengine forum if the original owner requests takedown it will be done otherwisethis is free for personal use". They don't appear to have asked for any permission nor do they seem to actually ask the owners if they care about this, or even ask if they use steam. Not sure what the rules are when it comes to re-uploading others' content, but even if the rules don't care, this is just generally a bit of a rude thing to do.

Maybe they're just porting the addons to make them more accessible to Steam users, but at the same time I can understand why the original creators may not like lexar1616 re-uploading (or possibly stealing) their addons.

EDIT: In the post called "Star Wars Addons", Quarior mentions someone posting their work on the Workshop, and they seem alright with it. 

There are some addons that are the result of collaboration, like the Star Wars addon. Others are work of individuals.
As a rule of thumb, whoever wants to make those addons available in workshop should make efforts with all possible means it has in contacting the original authors and ask for permission. Being material available in this forum, a request for permission via PM seems the viable option.

If no one is responding after a while, and I'd chek also in their profile if the user has not logged in for quite some time, then the conversion of the addon for its fruition in workshop, provided it's working as intended, could be fair use from my point of view.

The user in question has specified with a rather standard disclaimer in those workshop addons that he will pull off those addons if the original creator makes that request. Here I'm hoping that the user tried indeed to contact the creator via PM before publishing that material, rather than use right away the lazy option of that standard disclaimer. The reason is that those creators could not have a steam account, thus a steam version of SpaceEngine, and simply be unaware of the contents of the workshop nor being able to request their material pulled off.

If that's the case, and someone wants to contact that user for such a request, feel free to contact me in PM and I'll report that request to the user via Steam.

Reminds me of when the Celestia community had a similar problem, when someone kept stealing Star Trek ships from a 3rd party and uploading to their site and showing them off in the pictures thread. Eventually the original author of those trek models found out and tried to intervene, with no luck iirc.

Maybe lexar1616 is the same thief?

longname ,Ive removed a few or changed visibility, someone has uploaded my interstellar addon as well multiple time.

i saw this as i was passing through , so i thought i'd clarify the situation . I am familiar with the user on steam through the use of discord and was one of the subscribers to one of his mods , basically in conversations on discord he [lexar1616] started receiving private comments harrasing him for reuploading on the steam workshop . According to him in another conversation he did make legit attempts to reach out to the original creators [especially the sdss mod on the old spaceengine forum] for permission to upload with consent . For why he suddenly pulled all of his mods this goes back to the private comments he started getting , basically {in his own words} received threats amounting to bodily harm / leaking personal information about where he lived .
 It was a hard sell just trying to convince lexar1616 just to upload the sdss mod again [ in his words on discord to me , ''As far as i'm concerned the spaceengine/steam community can go screw itself as apparently they have no appreciation for attempting to save mods from disappearing ''] 

Blame it on incommunicability between users, not to the spaceengine community.
I'm a moderator on Discord and personally I have only seen steam addons with poor descriptions appearing, disappearing, changing names and users without a clue about what was happening.
If he received threats from discord users, I hope he followed proper channels for the application of rules and ToC, which means that those users should probably be banned by now, if he didn't he should have contacted someone else.
The same goes with steam channels of course.