Extremely high data useage

Hello, so recently I've been using this app called Zynn to try and make a few dollars by doing their referral challenge because it gives you 6 dollars per invite so I downloaded the app and went along with inviting people. However, when I checked my data an hour ago I saw that my data use was 390 GB which is insane because I never used that much. In fact, I've barely used over 5 GB from the beginning of this month. Another thing is that this all happened within a few days because around 2-3 days ago when I checked my data everything was normal at 5.6GB. The usage seems to be coming from YouTube with over 100GB from there, but there are some other bizarre numbers as well. For example 160GB were from uninstalled apps which I can't view, this is strange because I never uninstalled any apps from the time when my data was at 5.8GB to now being at 390GB. The other thing is that my hotspot was at 48GB which is also strange because I never shared my data with anyone and when I checked my hotspot was turned off. Now I'm not blaming it 100% on the app Zynn but I have noticed that the app would randomly play when my device was off. Even on my iPad which I also had the app installed on. After this I quickly installed the app on all devices that I had it on and I really need some help because this is stressing me out so much. One final thing I want to point out is that I always have cellular turned on but this shouldn't be an issue because I'm always connected to WiFi. Even so the numbers the settings displayed were all abnormal. Sorry for such a long paragraph but I just wanted to make sure that what I was dealing with could be repairable.