I'd love to find the original thread the article cites, but their link just leads back to the article.

i'd like to know which terraria mods.

edit: killer57 has found the effected mod in the thread below. (Stormdark UI)

Then host them somewhere else. Steam is gatekeeping mods; you can't download them if you have the game from somewhere else, except with the cumbersome steamcmd cli tool made for servers.

I'm confused by this article - Cities Skylines 2 doesn't use the Steam workshop, so how could dmca notices in steam affect it? The article title says CS but the body says CS2.

Did they mean Cities Skylines 1? Or did they mean dmca notices had been placed on Paradox Mods (which hosts CS2 mods)?

It feels like this is poor quality misreporting of the situation. On googling it seems to be Steam Workshop so probably Cities Skylines 1?