In addition, mods always end up in a situation where someone’s work was stolen, which no one cares about when it’s free. Everyone’s just using everyone else’s stuff because it’s all working to make a better ecosystem

Taken from https://creations.bethesda.net/en/creators/bethesdagamestudios

Creations can range anywhere from simple cosmetics or gameplay tweaks to entire new quests and encounters - it's up to what you can conjure! Our internal document available to Verified Creators has some specifics, but in general:

Creations must be standalone, so it cannot depend on other community releases, free or paid.

Creations must be all-new to qualify for release. You cannot re-purpose older releases – or work by other authors, unless contracted.