Rather odd MGM would take issue with these fan re-creations because in unedited gameplay (I specify this because if you watch the videos by YouTuber Graslu00 the music and voices in those gameplay videos were edited by Graslu themselves) the levels are using absolutely no assets from Goldeneye, it's all assets that Ubisoft created (as far as I can tell there is no asset importing in Far Cry 5's level editor, it uses content only from Ubisoft games).
Now I should note that the maker behind the maps is re-editing them to remove any mentions of characters and such relating to Goldeneye in order to get around MGM's claims, namely they're renaming the maps to "Golden Cry" and use slightly altered character names, so soon enough the maps should be fully back on Ubisoft's "Far Cry Arcade" service for FC5.