Yes, there were lots of other issues, but what I'm mostly referring to was that many of these broken systems wouldn't have to be built if stuff like DOTS and virtual texturing wasn't unfinished:

And the reason why the game has its own culling implementation instead of using Unity’s built in solution (which should at least in theory be much more advanced) is because Colossal Order had to implement quite a lot of the graphics side themselves because Unity’s integration between DOTS and HDRP is still very much a work in progress and arguably unsuitable for most actual games. Similarly Unity’s virtual texturing solution remains eternally in beta, so CO had to implement their own solution for that too, which still has some teething issues.