My 2021 Toyota Highlander, purchased with 16k miles, has a leak in the AC system in the rear of the vehicle (as of May 2025, at 3 years 10 months into the vehicle’s service, with 28k miles). This pipe runs the length of the car and costs $2000-$3000 to repair. This was confirmed at an independent service center that used leak detection dye to identify the problem. I am finding multiple reports of people having this problem in young Toyota vehicles (<4 years old) and with low miles. I believe this is a design flaw and not indicative of normal corrosion, as the vehicle does not exhibit corrosion elsewhere in the under carriage.