Does Checking Firebase Custom Claims in Flutter every 10 Minutes Cost A Lot of Money for 10K Users?

I am using Firebase customClaim to check user’s device id to prevent multi-devices use by one account. So I checked it using getIdTokenResult() for every 10 minutes. Now, I am worried if my app will have 10K users then the operational fee will be a lot. Does it really cost a lot? If it does, is there a way to cut down the cost? Thank you for helping me out.

     await user!.getIdTokenResult(false).then((result) {
        if (result.claims!.isNotEmpty) {
            idClaim = "${result.claims!["id01"]}";
            if(idClaim == deviceID){
              //Do not logout!
            } else {
              //Logout automatically
            }
        } else {
          // Send error message
        }
     }

>Solution :

There is no cost incurred by Firebase for this code. The pricing documentation is clear that Firebase Authentication is free to use except for certain operations.