Earlier quoted context omitted.
Block out IPv6 and see if that helps.
Why not block all odd v4 addresses while you're at it? I heard that that can reduce scraping volume by 50%!
It's easier and better to just block 0.0.0.0/1 half of the time, and 128.0.0.0/1 for the other half of the time. Switch every day at noon.
Bot traffic will be cut by 50%, and humans are all treated equally! It's a total win!