From android documentation,

ANDROID_ID

On Android 8.0 (API level 26) and higher versions of the platform, a 64-bit number (expressed as a hexadecimal string), unique to each combination of app-signing key, user, and device.

Here what does "user" mean?

CodePudding user response：

unique to each combination of app-signing key, user, and device https://developer.android.com/reference/android/provider/Settings.Secure#ANDROID_ID.

CodePudding user response：

Later in the same docs:

On devices that have multiple users, each user appears as a completely separate device, so the ANDROID_ID value is unique to each user.

And following the link there:

Android now allows multiple user spaces on shareable devices such as tablets. Each user on a device has their own set of accounts, apps, system settings, files, and any other user-associated data