The captions suck too. I subscribed to the same deal as you. I did it mostly to support the creators. But I basically never use it. The creator whose affiliate link I used to sign up? Their own captions are amazing on YouTube (human written with colour and positioning) and auto generated garbage on Nebula.
Do custom ROMs still have issues with some apps not allowing them? It’s been an eternity since I tried one and I don’t know if it’s a hard requirement, but at least when I did try it, I had (?) to root my device and my bank apps refused to work after that.