Hi,
I had almost the same with my old GS450H 2007 (full lexus history) but according to Lexus service center my problem was gearbox - pump failure at gearbox. The price was £8000 to repair. The main problem was that when I stop at traffic light for example, the car doesn’t move, i had to restart the car and it works again. I refused this repair and took the car to other specialist...they held the car for quite long time and tried to replace gearbox (it would cost me £1200) but failed. I then found someone who bough my car for a good price (independent car garage).
When you repair your issue, get rid off the car but warn the customer (just to be nice) 🙂
Ps. Unfortunately, Hybrid car manufactures (Toyota) gives only 10 years for hybrid system.