https://www.carcomplaints.com/Toyota/Sienna/2011/steering/steering.shtml
https://repairpal.com/the-power-steering-eps-in-our-2011-toyota-sienna-is-dead-391
You can try to collect more information and connact with Toyota to fix it for free. This looks like their design or quality issue, should take care of your problem. And this is good for Toyota for further huge cost.
Good luck!