I notice that the Borg population growth rate has been greatly reduced. While that's fine and fits with their mechanic, in my last play I lost between 50 and 75 percent of the population of any planets I conquered! I thought this might be because they were being driven off by low habitability, so I made a mod to grant the Collective a version of Tomb World Habitability for assimilated planets so that their un-assimilated pops weren't driven off world. However, that didn't work.
Losing up to 75 percent of a planet's population combined with the very low pop growth meant that I found it extremely difficult to populate my planets - the unicomplexes can only generate so many drones at a more or less normal rate! This is further exacerbated by not being able to build maturation chambers on planets. I feel that the Borg should be able to assimilate the entire population of the planets that they conquer to help counteract their low growth rate. I have some other ideas for the Borg, but I'll post them in the suggestion thread.
Another bug (that ironically helped solve the above-problem) was that when I assimilated a Kobali planet, their population doubled every month until all tiles were filled! It sure helped me populate the Collective, but that seems like something that shouldn't happen!