I have a 2016 Hyundai Tucson with about 50k miles on it. I had an oil change on 7/3. I started hearing the noise last week. It sounds like someone hitting a rock against the engine ONCE. I don’t hear the knocking while I’m driving. Also, I can only hear the noise when I start my car in my job’s underground parking garage. I don’t hear it when I start the car in front of my house etc.
Video link: https://www.youtube.com/watch?v=kiO1_QlLakY
The sound comes at the :10 mark