Color banding glow in after effects transparent video

I am trying to animate lanterns swininging and glowing which is then going to be imported into premiere pro where effects are added on the background. I have exported the trasparent video, but the result was very grid like and not smooth. I need it to be transparent for overlays and the glow needs too be smooth too. I read that color + alpha makes smooth lights have color banding, but the video has to be transparent since color key makes it look really choppy.

Is there also anyway to have a smaller file size, this 30 second video is 9 GB?

- The glowing effect is a png of a brush with 0% hardness imported into after effects

- I have other animations that I will import under this animtion in premiere pro