How do apps identify a device?

Question

Android

Hello.
Tell me, please, how exactly do applications identify devices?
Let's say I install the application, then delete it, change the play market account and, in principle, in Google services, and the application sees what was previously used on this device. How does this happen and how to get around it?
Curious:
What do I need this for?)
- Apps like Yakitoria give a 20% discount on the first order through the app. And many similar restaurants/deliveries/shops.

Answer 1

There is a software on w3bsit3-dns.com that changes the hardware parameters of the phone.
Find it and use it. Of course you need root.

Answer 2

As far as I remember, AndroidID is generated on hard reset. But, this will only help if the application uses it.

Answer 3

Mac address.
To get it, you only need permissions to a fine location. For the user, it looks like a fairly understandable solution.
1. Request Wi-Fi permissions
2. Get a Mac address (like WiFiInfo.getMacAddress())
3. Check if the Mac address is stored on the server.
4. If the server has such a poppy address - load the context for the application from the server, if not saved - generate the context and save it with the Mac address to the server.