I am using an After Effects comp in my Premiere timeline but when I render it the glows become banded even when uncompressed. If I render from After Effects the glows look fine.
I am using the DSLR 30 preset. 1920 x 1080 (1.0) 29.97fps
My guess is you're looking at the limitations of 8 bit video on the Premiere Pro side of things.
I exported the AE comp as a Tiff with Alpha image sequence and used that in my Premiere timeline and that gave me good results. It is too bad I have to render it twice to get it to work well.