TelephonyManager.allCellInfo returns all cell despite createForSubscriptionId

Question

I'm not sure if it's normal, but even though I instantiated a specific TelephonyManager for each of my SIM cards (with the subscriptionId), calling allCellInfo returns all cells detected by the device.

I use these APIs to monitor cells with CellInfo objects. Our algorithm is now quite easy: a timer running every second retrieve CellInfo objects through 2 APIs:

• for Android Q+, requestCellInfoUpdate which works well
• for older versions, I fallback to allCellInfo

We used to listen to callbacks using PhoneStateListener, but it works erratically depending on manufacturers and devices (some Samsung devices for example).

Possible solutions:

• filter CellInfo on MCC/MNC: impossible as some carriers share networks. Don't know if a customer of "carrier #1" sees an antenna from "carrier #2" with MCC/MNC from "carrier #1" or "carrier #2".
• re-use PhoneStateListener / TelephonyCallback: TelephonyCallback may be working correctly, but it's only available since Android S. PhoneStateListener added a complexity to our algorithm (if it doesn't give us the right answer, then fallback to the timer). That's why we decided to remove this logic.

Does anyone have a solution to suggest to make work allCellInfo as intended?