What I find odd is that on the 2 occasions I've used a CTEK to fully charge the 12V battery after not using the car for a couple of weeks, on next powering up the battery segments go right up to max then tail off during driving back to the normal 3 to 6 variable segments.
This mentioned in user manual on page 138
When car used for 30 minutes HV battery will by cycled many times from 29% to 70% or less depends on conditions but at the end of this drive cycle HV battery will be the same ~30-40% SOC (so mayby not charge level concern but balancing liion pack because if pack unbalanced pack will stop working with hybrid system check error on dashboard) - liIon battery have very low self discharge rate and when car not used almost not discharges.
Another story if for some reasone when car in ready state driver moving from Drive (D) to Neutral (N) in this case ICE engine will stop charging HV battery and HV battery may by discharged by car loads such as A/C (directly uses HV DC) seat heaters and rear window heater (powered throught DC-DC converter that suply charge to 12v system) below the point when car can start ICE to recharge HV battery.
Loock on Toyota recommendation for hybrids (but they mention both batteryes just because many their hybrids uses HV NiMh packs this ones have huge self discharge rate in comparison with LiIon packs -
https://mag.toyota.co.uk/coronavirus-toyota-hybrid-car-maintenance/They simple asked to turn on car to ready state for 60 minutes.