Come on man, no need to make assumption when the ultra feature are listed there in the app setting. At a glance you can see the ones that are potential money sink are push notifications (money goes to firebase/Google), Google translate (money goes to Google), OCR (money goes to GPU vps providers). The original sync ultra even have restore deleted comments option, which mean they was practically mirror Reddit public dataset. At $17 per year or ~$100 lifetime, it's very reasonable, which includes paying the dev as well.