Hi, as suggested in another topic, (I cannot put a link for some reason), I created a new topic.
The app is not optimized for the iPhone XS Max and iPhone XR, as they have a different screen resolution with respect to previous devices, so the app renders at the resolution of iPhone X and iPhone XS and then it's scaled up to the one of the screen.
Personally, on an iPhone XS Max, given the high screen density, the scaling is not very noticeable, but it's good to fix it anyway.
To "reproduce" you just need to be in the app in any place. You can better notice it by looking at the keyboard in Spotify and in the spotlight. You should see the keyboard in Spotify is bigger.