Coolant loss

Because this recent article is under pay wall, here's entire Q and A - "Q. I have a 2018 Toyota Prius Prime (only 89,000 miles) and twice now I had to add coolant to the engine. When this happens, I don’t get much heat out of the heater and sometimes the check engine light comes on. I add coolant and all is fine again until it isn’t. I took it to a hybrid repair shop, and they told me it could be a problem with the exhaust heat exchanger, and it will be expensive to repair. I purchased this car to save money of gas, not pay for expensive repairs. How common is this?
A. If in fact the exhaust heat exchanger is leaking the repair is covered under the California (most Northeast states) emissions warranty. This warranty covers certain components for 180 months or 150,000 miles whichever comes first. Return to a Toyota dealer and have them check out the problem and reference TSB 0135-19"
https://www.saratogian.com/2022/01/22/questions-and-answers-from-the-car-doctor-53/?fbclid=IwAR1RkaJKJZuctvkl3vaYB2A-Hl3_ZJJjj1Ba45YdW6xfeYUK5imnZTGhmno

 

Here's Toyota Technical Service Bulletin. Note: for 2017-2019 PPs only. This repair is covered under the Toyota Federal Emission Warranty. This warranty is in effect for 96 months or 80,000 miles, whichever occurs first, from the vehicle’s in-service date. Prius Prime vehicles, sold, registered, and normally operated in California, Connecticut, Maine, Maryland, Massachusetts, New Jersey, New York, Oregon, Rhode Island, and Vermont. The California Emissions Defect and Performance Warranty coverage is 180 months from the date of first use or 150,000 miles (whichever occurs first). https://static.nhtsa.gov/odi/tsbs/2019/MC-10166037-9999.pdf