2013 Sonata MPG down by 10

I have a 2013 Hyundai Sonata. I’ve put about 20k miles on it. In October, I slowly noticed that my MPG went from 30-35 driving normally to barely above 25 driving conservatively. The engine sounds like it’s working harder than it needs to. The RPMs do NOT go down while coasting. It seems like the rpm’s are now speed dependent and has nothing to do with how much gas I’m applying. They used to go down to less than 1.5k while coasting above 60mph. Now, when I’m on the highway the rpm’s are always at 2k plus at LEAST. And they continue to go up as my speed increases, regardless of if I’m coasting. It wasn’t always like this! This problem happened basically overnight. Please help