Apps generally have a lot more access to the user info than Web sites. I remember getting into an argument, here (one-sided, I didn't argue then, and I won't now), about how a Web site is just as intrusive and privacy-endangering as an app (I think they wrote PWAs, and didn't want to cede the point to native apps). I feel they were wrong. Apps can get more information than web sites; even with sandboxing.

In my experience, apps can figure out a lot more about the user, than a Web site.

I just reported a game to Apple, that, after the app has been resident for 24 hours, pops up an unescapable modal to sign into their Web site. I am sure the 24-hour delay, is so they don't get caught by the App Store folks. I suspect that what happens, during this "daily checkin," is that the app sends a bunch of encrypted data that it got from your device, to the servers in China.

Basically, they can learn more about you from the app, than from the Web site.

I generally avoid apps, where the Web site will do. I won't install banking apps, at all.