Giftfish, one of the more prominent mod creators for the original Mass Effect games, has pulled all of their mods from Nexus Mods. Their reason for doing this is to avoid other creators freely remaking those mods for the newly-released Legendary Edition.
In a blog post released on their website on May 14th (the same day that Legendary Edition released,) Giftfish said that she spoke to mods at Nexus Mods about their concerns over mod "ports." Mass Effect modders can't port their mods like Skyrim modders could do with the Special Edition, and they have to remake the mods with Legendary Edition's files. However, Giftfish says that Nexus considers remaking a mod "idea-based" and not something restricted to only the original mod's creator, so cases of mod infringement would always need to be handled on a case-by-case basis. "Mass Effect modders can’t port our mods; we can only re-make our mods," she said. "Yet, Nexus will not recognize our exclusive right to re-make our mods, deeming the concept 'idea-based.'"
Giftfish continues that because of this lack of protection against infringement, she is stepping away from the modding scene and have removed all of their mods from Nexus Mods. They are most known for mods like ThaneMOD, which was one of the first story-enhancing gameplay mods for Mass Effect 3. Despite there being a download link on the official ThaneMOD website, it leads to a Nexus Mods page saying the mod is no longer available for download.
Some people may not think that it's too hard to recreate the mods for Legendary Edition, but as Giftfish explains in two of their previous blog posts, that's not the case. That second link in particular explains that, unlike the highly-modded Skyrim and its Special Edition remaster, Mass Effect has many more files and it's much easier for mod conflicts to happen.
Mass Effect: Legendary Edition released May 14th on Steam, Xbox One, and PlayStation 4.