The thing that really baffled me (spoilers for the movie, if you haven't been spoiled yet) is how little we saw of Bubble in the movie. In fact, I don't think he showed up at all.
It seemed like the last episode was setting Bubble up as the big villain. The first AI that maybe Caine had the job of placating or controlling, salvaging his random, crazy output into something coherent ("his purpose" as he put it) you could even make out Bubble taunting Kinger and forcing him to delete Caine in the screencaps.
So it seemed like the setup was that Bubble got rid of Caine and was about to go wild, whether that meant something as grand as warping the circus in his twisted image, or something as small and simple as letting the abstractions out and using light to make them go ballistic.
It seemed like they were setting up Caine's arc to be that Bubble was the devil on his shoulder that was making him do everything wrong, but he was so devoted to his "purpose" that he couldn't get rid of him, and they even seem to play with that by having Caine remove the blue thing from his head and toss it into the void -- but they don't do anything to elaborate on how or why.
But other than Caine pulling a blue marble out of his head and tossing it aside, it doesn't seem like they did anything with what the last episode set up.
Like I get that authors are allowed to have preferences in what characters and things they write about, but there's a big difference between that and just straight up leaving your story unfinished.
