Kia Motors complaint: Catalytic converters

I bought my daughter a new Kia Sportage for her 40th birthday in 2019. It now has 82 thousand plus miles. She has had trouble with it being a little sluggish going up hill for about over a yr. She took it to a dealer in Nicholasville Ky. They check it bc the engine light was on she told them about the sluggishness. They checked it said it was ok could turn the engine light off but would be a charge. They said it would not hurt to leave it on. So due to financial reasons she said if it is ok I just leave it on. Now a few months later took it to another Kia dealer due to it only going 40mph when going up a hill. Another Kia dealer said the catalytic converters are out. Unreal that this was not located before warranty is out. The reason she didn’t take it back to Nicholasville was bc of their poor repair service customer service.