Mileage went off a cliff

The mileage of my 2014 SF (3 row) went from 23+ to around 17 right around the time it went in for new tires (same size) and an oil change at a shop we've used for decades. I tried a gas treatment to clean the injectors with no result. Took it to the local dealer who verified the engine air filter had been changed and found nothing wrong, though they did try to sell a $90 cleaning kit despite the gas treatment.

I have confirmed the lower mpg manually; I'm still using the Eco driving setting; and my driving style hasn't changed.

Any ideas?