Unexpected $1,500 bill for September due to child branches

On September's invoice we had a $1,500 bill for our NeonDB account, most of which was related to child branch storage. The main branch weights 9.43 GB, and we had 4 sandbox branches forked from it which were all above 8 GB. The older their last activity was, the lower their weight This is really unexpected because we've had this pattern for the last few months, and I don't see why these branches forked from main would have the same weight, as to my knowledge we did not rewrite all the data in the last few days. This seems to coincide with the new plan rollout: https://neon.com/blog/new-usage-based-pricing Is it possible that some bug in the migration could have caused a system to incorrectly attribute this weight to our child branches? How can I see a more fine-grained analysis of the cost?