Likely due to the heater(s). Will mentioned that recently in a video about the SOK heated battery.
Given my northern latitude, I plan to get the heated version. If you heat directly from the BMS, it should not create unbalance bewteen the different banks because they are all still connected in parallel. My plan was to let the BMS heat function drive a relay so that the actual load was coming from the power buss so it would be directly shared by all batteries.