Weta was an entity of its own for longer than Unity as a company has been around. Unity bought them (well, the tech assets) as a reaction to Epic moving into and firmly setting up shop in the film business.
I mean, Mandalorean had already shot season one with Epic's tech before Unity woke up and decided/realised that it's being left behind [1].
Unity is a game engine company that hasn't produced a single game, moving into film making tools by never producing, and only acquiring, film making tools as a reaction to competition. Competition is good, but is Unity a company that can actually compete in this space? I hope so, but I wouldn't hold my breath.
[1]
Epic already boasting about it in early 2020 https://www.unrealengine.com/en-US/blog/forging-new-paths-fo...
Unity announcing aquisition in late 2021 https://blog.unity.com/news/welcome-weta-digital